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'''Evidence-based medicine''' is ''"the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients."''.<ref name="pmid8555924">{{cite journal |author=Sackett DL ''et al.''|title=Evidence based medicine: what it is and what it isn't |journal=BMJ |volume=312 |pages=71–2 |year=1996 |pmid=8555924 |doi=}}</ref> Alternative definitions are "''the process of systematically finding, appraising, and using contemporaneous research findings as the basis for clinical decisions''"<ref name="pmid1404801">{{cite journal |author= |title=Evidence-based medicine. A new approach to teaching the practice of medicine. Evidence-Based Medicine Working Group|author=Evidence-Based Medicine Working Group |journal=JAMA |volume=268 |pages=2420–5 |year=1992 |pmid=1404801 |doi=}}</ref> or "''evidence-based medicine (EBM) requires the integration of the best research evidence with our clinical expertise and our patient's unique values and circumstances''."<ref name="isbn0-443-07444-5">{{cite book |author=Glasziou, Paul; Strauss, Sharon Y. |title=Evidence-based medicine: how to practice and teach EBM |publisher=Elsevier/Churchill Livingstone |location= |year=2005 |pages= |isbn=0-443-07444-5 |oclc= |doi=}}</ref>  Better known as EBM, evidence based medicine emerged in the early 1990s.
'''[[Evidence]]-based [[medicine]]''' is ''"the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients."''<ref name="pmid8555924">{{cite journal |author=Sackett DL ''et al.''|title=Evidence based medicine: what it is and what it isn't |journal=BMJ |volume=312 |pages=71–2 |year=1996 |pmid=8555924 |doi=}}</ref> Alternative definitions are "''the process of systematically finding, appraising, and using contemporaneous research findings as the basis for clinical decisions''"<ref name="pmid1404801">{{cite journal |author= |title=Evidence-based medicine. A new approach to teaching the practice of medicine. Evidence-Based Medicine Working Group|author=Evidence-Based Medicine Working Group |journal=JAMA |volume=268 |pages=2420–5 |year=1992 |pmid=1404801 |doi=}}</ref> or "''evidence-based medicine (EBM) requires the integration of the best research evidence with our clinical expertise and our patient's unique values and circumstances''."<ref name="isbn0-443-07444-5">{{cite book |author=Glasziou, Paul; Strauss, Sharon Y. |title=Evidence-based medicine: how to practice and teach EBM |publisher=Elsevier/Churchill Livingstone |location= |year=2005 |pages= |isbn=0-443-07444-5 |oclc= |doi=}}</ref>  Better known as EBM, evidence based medicine has roots in clinical [[epidemiology]] and the [[scientific method]], and emerged in the early 1990's in response to discoveries about variations and deficiencies<ref name="pmid18361259">{{cite journal |author=Thier SL, Yu-Isenberg KS, Leas BF ''et al'' |title=In chronic disease, nationwide data show poor adherence by patients to medication and by physicians to guidelines |journal=Manag Care |volume=17  |pages=48-52, 55-7 |year=2008 |pmid=18361259 |doi= |issn=}}</ref> in medical care to help healthcare providers and policy makers evaluate the efficacy of different treatments.


Evidenced-based practice is not restricted to medicine among the health sciences, dentistry, nursing and other allied health science are adopting "evidence-based medicine" as well.''Evidence-Based Health Care'' or ''evidence-based practice'' extends the concept of EBM to all health professions, including purchasing and management [http://www.cebm.net/glossary.asp].
Evidence-based practice is not restricted to medicine: [[dentistry]], [[nursing]] and other allied [[health science]] are adopting "evidence-based medicine" as well as [[alternative medicine|alternative medical]] approaches, such as [[acupuncture]]<ref name="pmid-17577006">{{cite journal |author=Manheimer E ''et al.'' |title=Meta-analysis: acupuncture for osteoarthritis of the knee |journal=Ann Intern Med |volume=146  |pages=868–77 |year=2007 |pmid=17577006 |doi= |issn=}}</ref><ref name="pmid-15998750">{{cite journal |author=Assefi NP ''et al.'' |title=A randomized clinical trial of acupuncture compared with sham acupuncture in fibromyalgia |journal=Ann Intern Med |volume=143  |pages=10–9 |year=2005 |pmid=15998750 |doi= |issn=}}</ref>.  ''Evidence-Based Health Care'' or ''evidence-based practice'' extends the concept of EBM to all health professions, including management<ref name="pmid-15647226">{{cite journal |author=Clancy CM, Cronin K |title=Evidence-based decision making: global evidence, local decisions |journal=Health Affairs (Project Hope) |volume=24  |pages=151–62 |year=2005 |pmid=15647226 |doi=10.1377/hlthaff.24.1.151}}</ref><ref name="pmid-15647225">{{cite journal |author=Shojania KG, Grimshaw JM |title=Evidence-based quality improvement: the state of the science |journal=Health Affairs (Project Hope) |volume=24  |pages=138–50 |year=2005 |pmid=15647225 |doi=10.1377/hlthaff.24.1.138}}</ref> and policy<ref name="pmid-16835176">{{cite journal |author=Fielding JE, Briss PA |title=Promoting evidence-based public health policy: can we have better evidence and more action? |journal=Health Affairs (Project Hope) |volume=25  |pages=969–78 |year=2006 |pmid=16835176 |doi=10.1377/hlthaff.25.4.969}}</ref><ref name="pmid-17978383">{{cite journal |author=Foote SB, Town RJ |title=Implementing evidence-based medicine through medicare coverage decisions |journal=Health Affairs (Project Hope) |volume=26 |issue=6 |pages=1634–42 |year=2007 |pmid=17978383 |doi=10.1377/hlthaff.26.6.1634}}</ref><ref name="pmid-15647221">{{cite journal |author=Fox DM |title=Evidence of evidence-based health policy: the politics of systematic reviews in coverage decisions |journal=Health Affairs (Project Hope) |volume=24  |pages=114–22 |year=2005 |pmid=15647221 |doi=10.1377/hlthaff.24.1.114}}</ref>.


==Why do we need evidence-based medicine?==
==Classification==
It is easy to assume that physicians always use scientific evidence conscientiously and judiciously in treating patients. In fact, most of the specific practices of physicians and surgeons are based on traditional techniques learned from their mentors in the care of patients during training. Additional modifications come from personal clinical experience, from information in the medical literature and continuing education courses. Although these practices almost always have a rational basis in biology, the actual efficacy of treatments is rarely tested by experimental trials in people. Further, even when the results of experimental trials or other evidence have been reported, there is a lag time between the acceptance of changes to medical practice and establishing them as routine in clinical care. Evidence-based medicine seeks to address these issues by promoting practices that have been shown to have validity using the [[scientific method]].
Two types of evidence-based medicine have been proposed:<ref name="pmid15647211">{{cite journal |author=Eddy DM |title=Evidence-based medicine: a unified approach |journal=Health Affairs (Project Hope) |volume=24 |pages=9-17 |year=2005 |pmid=15647211 |doi=10.1377/hlthaff.24.1.9}}</ref>


==Steps in evidence-based medicine==
* ''Evidence-based guidelines'', EBM at the ''organizational or institutional'' level, which involves producing [[clinical practice guideline]]s, policy, and regulations;
===Ask===
"'''Ask'''" - Formulate a well-structured clinical question.


===Acquire===
*''[[Evidence-based individual decision making]]'', EBM as practiced by an individual [[health care provider]] when treating an individual patient. There is concern that evidence-based medicine focuses excessively on the physician-patient dyad and as a result miss many opportunities to improve healthcare.<ref name="pmid15647211"/>
The ability to "'''acquire'''" evidence in a timely manner may improve healthcare.<ref name="pmid17971885">{{cite journal |author=Banks DE ''et al'' |title=Decreased hospital length of stay associated with presentation of cases at morning report with librarian support |journal=Journal of the Medical Library Association : JMLA |volume=95 |pages=381–7 |year=2007 |pmid=17971885 |doi=10.3163/1536-5050.95.4.381 |issn=}}</ref> Unfortunately, doctors may be led astray when acquiring information as often as they find correct answers.<ref name="pmid16929042">{{cite journal |author=McKibbon KA, Fridsma DB |title=Effectiveness of clinician-selected electronic information resources for answering primary care physicians' information needs |journal=Journal of the American Medical Informatics Association : JAMIA |volume=13 |pages=653–9 |year=2006 |pmid=16929042 |doi=10.1197/jamia.M2087}}</ref>


A proposed structure of the evidence search is the 5S search strategy,<ref name="pmid17080967">{{cite journal |author=Haynes RB |title=Of studies, syntheses, synopses, summaries, and systems: the "5S" evolution of information services for evidence-based health care decisions |journal=ACP J Club |volume=145 |pages=A8 |year=2006 |pmid=17080967 |doi=}}</ref> which starts with the search of "summaries" (textbooks). A randomized controlled trial supports the efficiency of this approach.<ref name="pmid17082828">{{cite journal |author=Patel MR ''et al.'' |title=Randomized trial for answers to clinical questions: evaluating a pre-appraised versus a [[MEDLINE]] search protocol |journal= JMLA |volume=94 |pages=382–7 |year=2006 |pmid=17082828 |doi=}}</ref>
==Justification==
Part of the justification for EBM is the unreliability about making clinical decisions using heuristics.<ref name="pmid19231086">{{cite journal| author=Aberegg SK, O'Brien JM| title=The normalization heuristic: an untested hypothesis that may misguide medical decisions. | journal=Med Hypotheses | year= 2009 | volume= 72 | issue= 6 | pages= 745-8 | pmid=19231086
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=19231086 | doi=10.1016/j.mehy.2008.10.030 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref><ref name="pmid7503478">{{cite journal| author=McDonald CJ| title=Medical heuristics: the silent adjudicators of clinical practice. | journal=Ann Intern Med | year= 1996 | volume= 124 | issue= 1 Pt 1 | pages= 56-62 | pmid=7503478
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=7503478 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref>


===Appraise===
==Steps in EBM==
To "'''Appraise'''" the quality of the answer found is very important as one third of the results of even the most visible medical research is eventually either attenuated or refuted.<ref name="pmid16014596">{{cite journal |author=Ioannidis JP |title=Contradicted and initially stronger effects in highly cited clinical research |journal=JAMA |volume=294  |pages=218–28 |year=2005 |pmid=16014596 |doi=10.1001/jama.294.2.218}}</ref> There are many reasons for this<ref name="pmid9546568">{{cite journal |author=Ioannidis JP ''et al.''|title=Issues in comparisons between meta-analyses and large trials |journal=JAMA |volume=279 |pages=1089–93 |year=1998 |pmid=9546568 |doi=}}</ref>; two important reasons are publication bias<ref name="pmid1727960">{{cite journal |author=Dickersin K, Min YI, Meinert CL |title=Factors influencing publication of research results. Follow-up of applications submitted to two institutional review boards |journal=JAMA |volume=267 |pages=374–8 |year=1992 |pmid=1727960 |doi=}}</ref> and conflict of interest<ref name="pmid15916457">{{cite journal |author=Smith R |title=Medical journals are an extension of the marketing arm of pharmaceutical companies |journal=PLoS Med |volume=2  |pages=e138 |year=2005 |pmid=15916457 |doi=10.1371/journal.pmed.0020138}}</ref>. These two problems interact, as conflict of interest often leads to publication bias.<ref name="pmid12775615">{{cite journal |author=Melander H ''et al.'' |title=Evidence b(i)ased medicine--selective reporting from studies sponsored by pharmaceutical industry: review of studies in new drug applications |journal=BMJ |volume=326 |pages=1171–3 |year=2003 |pmid=12775615 |doi=10.1136/bmj.326.7400.1171}}</ref><ref name="pmid1727960">{{cite journal |author=Dickersin K ''et al.''|title=Factors influencing publication of research results. Follow-up of applications submitted to two institutional review boards |journal=JAMA |volume=267 |pages=374–8 |year=1992 |pmid=1727960 |doi=}}</ref>
:''See also [[Teaching evidence-based medicine]]''
{|align="right" cellpadding="10" style="background-color:#FFFFCC; width:50%; border: 1px solid #aaa; margin:20px; font-size: 92%;"
|''The 5 S search strategy''<ref name="pmid17080967">{{cite journal |author=Haynes RB |title=Of studies, syntheses, synopses, summaries, and systems: the "5S" evolution of information services for evidence-based health care decisions |journal=ACP J Club |volume=145 |pages=A8 |year=2006 |pmid=17080967 |doi=|url=http://www.acpjc.org/Content/145/3/issue/ACPJC-2006-145-3-A08.htm}}</ref>


However an obvious important reason is that many (if not all) studies contain potential flaws in their design, and even when there are no clear methodological flaws, any outcome of a test that is evaluated by statistical test has a margin of error: this means that some positive outcomes will be "false positives".
'''Studies''': original research studies that can be found using search engines like PubMed.


====Publication bias====
'''Synthesis''': systematic reviews or Cochrane Reviews.
Whether a treatment or medical intervention is effective or not may be judged either on the basis of the experience of the practising physician, or on the basis of what has been published by others. The publications with greatest authority are generally those that appear in the peer-reviewed scientific journals, and particularly in those journals generally thought to have the highest standards of editorial scrutiny. However, it is no simple matter to get a study published in any peer-reviewed journal, least of all in the best journals. Accordingly, many studies go unreported. It is often thought to be particularly difficult to publish small studies, the outcome of which conflicts with the reported outcomes of larger prviously published studies, or to publish studies where the outcome is equivocal - where no clear conclusion can be drawn. In part this reflects the wish of the best journals to publish influential papers, and in part it reflects simply the fact of authors choosing not to put their energies into publishing studies that are thought to be uninteresting. Such ''publication bias'' is can be very difficult to recognise, but its effects generally are to tend to encourage publication of studies that support an already formed conclusion, while tending to discourage publication of contradictory or equivocal findings.<ref name="pmid1727960">{{cite journal |author=Dickersin K ''et al.'' |title=Factors influencing publication of research results. Follow-up of applications submitted to two institutional review boards |journal=JAMA |volume=267 |pages=374–8 |year=1992 |pmid=1727960 |doi=}}</ref><ref name="pmid12876092">{{cite journal |author=Krzyzanowska MK ''et al.''|title=Factors associated with failure to publish large randomized trials presented at an oncology meeting |journal=JAMA |volume=290 |pages=495–501 |year=2003 |pmid=12876092 |doi=10.1001/jama.290.4.495}}</ref> Publication bias may be more prevalent in industry sponsored research.<ref name="pmid12775614">{{cite journal |author=Lexchin J ''et al.''|title=Pharmaceutical industry sponsorship and research outcome and quality: systematic review |journal=BMJ |volume=326 |pages=1167–70 |year=2003 |pmid=12775614 |doi=10.1136/bmj.326.7400.1167}}</ref>


In performing a [[Meta-analysis|meta-analyses]], a file drawer<ref name="pmid11523382">{{cite journal |author=Pham B ''et al.'' |title=Is there a "best" way to detect and minimize publication bias? An empirical evaluation |journal=Evaluation & the Health Professions |volume=24 |issue=2 |pages=109–25 |year=2001 |pmid=11523382 |doi=}}</ref> or a funnel plot analysis<ref name="pmid9310563">{{cite journal |author=Egger M ''et al.'' |title=Bias in meta-analysis detected by a simple, graphical test |journal=BMJ |volume=315 |pages=629–34 |year=1997 |pmid=9310563 |doi=}}</ref><ref name="pmid16085192">{{cite journal |author=Terrin N ''et al.'' |title=In an empirical evaluation of the funnel plot, researchers could not visually identify publication bias |journal=J Clinical Epidemiol |volume=58 |pages=894–901 |year=2005 |pmid=16085192 |doi=10.1016/j.jclinepi.2005.01.006}}</ref> may help detect underlying publication bias among the studies in the meta-analysis.
'''Synopses''': in EBM journals, ACP Journal club etc. give brief descriptions of original articles and reviews as they appear .


====Conflict of interest====
'''Summaries''':  in EBM textbooks integrate the best available evidence from syntheses to give evidence-based management options for a health problem.  
In any publication, there is always some issue of conflict of interest. Academic scientists gain their professional reputations by publishing, and it is always in their interest to be seen to be publishing interesting and important findings. They also have to answer to their sources of funding, whether the studies are funded by charities, public bodies or private industry. Accordingly all scientists are under pressure to publish, and under pressure to report and perhaps overstate any outcomes that might seem to be noteworthy; flat and purely factual summaries do not necessarily impress journal editors any more than they inspire casual readers.  


However, when studies are funded by private industry there is inevitably some suspicion that they might be tainted by that association. In other words, when a particular outcome of a trial might lead to commercial advantage for its sponsor, will there not be some tendency, however inadvertent, to bias the design of the trial or bias its analysis to favour the desired outcome?
'''Systems''': e.g. computerized decision support systems that link individual patient characteristics to relevant evidence.
|}
===Ask===
To "'''ask'''" and formulate a well-structured clinical question, i.e. one that is directly relevant to the identified problem, and which is constructed in a way that facilitates searching for an answer. The question should have four 'PICO' elements<ref name="pmid7582737">{{cite journal| author=Richardson WS, Wilson MC, Nishikawa J, Hayward RS| title=The well-built clinical question: a key to evidence-based decisions. | journal=ACP J Club | year= 1995 Nov-Dec | volume= 123 | issue= 3 | pages= A12-3 | pmid=7582737
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=clinical.uthscsa.edu/cite&retmode=ref&cmd=prlinks&id=7582737 }} </ref><ref name="pmid17238363">{{cite journal |author=Huang X, Lin J, Demner-Fushman D |title=Evaluation of PICO as a knowledge representation for clinical questions |journal=AMIA Annu Symp Proc |volume= |issue= |pages=359–63 |year=2006 |pmid=17238363 |pmc=1839740 |doi= |url= |issn=}}</ref>: the patient or problem ('''P'''); the medical intervention or exposure (e.g., a cause for a disease) ('''I'''); the comparison intervention or exposure ('''C'''); and the clinical outcomes ('''O'''). The better focused the question is, the more relevant and specific the search for evidence will be.<ref name="pmid17573961">{{cite journal |author=Schardt C, Adams MB, Owens T, Keitz S, Fontelo P |title=Utilization of the PICO framework to improve searching PubMed for clinical questions |journal=BMC Med Inform Decis Mak |volume=7 |issue= |pages=16 |year=2007 |pmid=17573961 |pmc=1904193 |doi=10.1186/1472-6947-7-16 |url=http://www.biomedcentral.com/1472-6947/7/16 |issn=}}</ref>


The responsibility for the integrity of the design and analysis of all studies lies squarely with the authors. If the academic and clinical scientists involved in any trial are lacking in competence or integrity, then indeed this might prejudice the value of the trial. It should be remembered that if any drug does have significant adverse effects, then it is very much in the interests of the pharmaceutical company manufacturing it that these be identified as quickly as possible, if only to minimise the very large costs of the inevitable eventual litigation. Thus, while it is in a pharmaceutical company's interests to report that its drug is better than a competitor's drug, or better than no treatment, it is very much not in their interests to suppress evidence of harm. However, for the scientists who are conducting the trials, things might seem a little different: if it becomes clear that a drug is useless or harmful, then the company will withdraw it and their funding for the studies will naturally cease. In the end, it is the integrity and competence of the academic and clinical scientists that determines the quality and value of trials, both for the public and indeed for their industrial sponsors.
===Acquisition of evidence===


In the design of [[randomized controlled trial]]s, industry-sponsored studies may be more likely to select an inappropriate comparator group that would favor finding benefit in the experimental group. In other words, there is a tendency for industry-sponsored trials to compare the effectiveness of their drug with the effectiveness of an established current treatment rather than with a direct competitor that might also be better than the current treatment chosen for comparison <ref name="pmid12775614">{{cite journal |author=Lexchin J ''et al.'' |title=Pharmaceutical industry sponsorship and research outcome and quality: systematic review |journal=BMJ |volume=326 |pages=1167–70 |year=2003 |pmid=12775614 |doi=10.1136/bmj.326.7400.1167}}</ref>
{| class="wikitable" align="right"
|+ Acquisition is difficult due to instability of medical knowledge<ref name="pmid16014596">{{cite journal| author=Ioannidis JP| title=Contradicted and initially stronger effects in highly cited clinical research. | journal=JAMA | year= 2005 | volume= 294 | issue= 2 | pages= 218-28 | pmid=16014596
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=16014596 | doi=10.1001/jama.294.2.218 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref><ref name="pmid12069563">{{cite journal| author=Poynard T, Munteanu M, Ratziu V, Benhamou Y, Di Martino V, Taieb J et al.| title=Truth survival in clinical research: an evidence-based requiem? | journal=Ann Intern Med | year= 2002 | volume= 136 | issue= 12 | pages= 888-95 | pmid=12069563
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=12069563 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref><ref name="pmid9413475">{{cite journal| author=Hall JC, Platell C| title=Half-life of truth in surgical literature. | journal=Lancet | year= 1997 | volume= 350 | issue= 9093 | pages= 1752 | pmid=9413475
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=9413475 | doi=10.1016/S0140-6736(05)63577-5 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref><ref name="pmid17638714">{{cite journal| author=Shojania KG, Sampson M, Ansari MT, Ji J, Doucette S, Moher D| title=How quickly do systematic reviews go out of date? A survival analysis. | journal=Ann Intern Med | year= 2007 | volume= 147 | issue= 4 | pages= 224-33 | pmid=17638714
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=17638714 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref><ref name="pmid11572738">{{cite journal| author=Shekelle PG, Ortiz E, Rhodes S, Morton SC, Eccles MP, Grimshaw JM et al.| title=Validity of the Agency for Healthcare Research and Quality clinical practice guidelines: how quickly do guidelines become outdated? | journal=JAMA | year= 2001 | volume= 286 | issue= 12 | pages= 1461-7 | pmid=11572738
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=11572738 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref><ref name="pmid11980521">{{cite journal| author=Lasser KE, Allen PD, Woolhandler SJ, Himmelstein DU, Wolfe SM, Bor DH| title=Timing of new black box warnings and withdrawals for prescription medications. | journal=JAMA | year= 2002 | volume= 287 | issue= 17 | pages= 2215-20 | pmid=11980521
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=11980521 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref>
! Type of publication!! Durability
|-
| style="text-align:center;font-weight:bold;" colspan="2"|Primary publications
|-
| Highly cited studies major [[scientific journal]]s<ref name="pmid16014596"/>|| The results from one-third are refuted or attenuated within 15 years.
|-
| Original studies in hepatology<ref name="pmid12069563"/>|| Half-life of truth was 45 years
|-
| Original studies in surgery<ref name="pmid9413475"/>||  Half-life of truth was 45 years
|-
| style="text-align:center;font-weight:bold;" colspan="2"|Secondary publications
|-
| [[Systematic review]]s<ref name="pmid17638714"/>|| Median survival is 5.5 years.<br/>7% may out of date when published<br/> 23% may be out of date within 2 years
|-
| [[Clinical practice guideline|Practice guidelines]] by the [[Agency for Healthcare Research and Quality|AHRQ]]<ref name="pmid11572738"/>|| Half-life of truth was 5.8 years
|-
| [[Food and Drug Administration]] New Drug Approvals<ref name="pmid11980521"/>|| 8% acquire a new black box warning. Half occur within 7 years
|-
| [[Food and Drug Administration]] New Drug Approvals<ref name="pmid11980521"/>|| 3% withdrawn. Half occur within 2 years
|}


Regarding the reporting of data in [[randomized controlled trial]]s, industry-sponsored studies may be more likely to omit [[intention-to-treat]] analyses.<ref name="pmid12775615">{{cite journal |author=Melander H ''et al.'' |title=Evidence b(i)ased medicine--selective reporting from studies sponsored by pharmaceutical industry: review of studies in new drug applications |journal=BMJ |volume=326 |pages=1171–3 |year=2003 |pmid=12775615 |doi=10.1136/bmj.326.7400.1171}}</ref>
The ability to "'''acquire'''" evidence, also called [[information retrieval]], in a timely manner may improve healthcare.<ref name="pmid17971885">{{cite journal |author=Banks DE ''et al.'' |title=Decreased hospital length of stay associated with presentation of cases at morning report with librarian support |journal=JMLA |volume=95 |pages=381–7 |year=2007 |pmid=17971885 |doi=10.3163/1536-5050.95.4.381 |issn=}}</ref><ref name="pmid15109337">{{cite journal |author=Lucas BP, Evans AT, Reilly BM, ''et al'' |title=The impact of evidence on physicians' inpatient treatment decisions |journal=J Gen Intern Med |volume=19 |issue=5 Pt 1 |pages=402–9 |year=2004 |pmid=15109337 |doi=10.1111/j.1525-1497.2004.30306.x |issn=}}</ref> Unfortunately, doctors may be led astray when acquiring information because of difficulties in selecting best articles<ref name="pmid15618105">{{cite journal |author=Rosenbloom ST, Giuse NB, Jerome RN, Blackford JU |title=Providing evidence-based answers to complex clinical questions: evaluating the consistency of article selection |journal=Acad Med |volume=80 |issue=1 |pages=109–14 |year=2005 |month=January |pmid=15618105 |doi= |url=http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?issn=1040-2446&volume=80&issue=1&spage=109 |issn=}}</ref>, or because individual trials may be flawed or their outcomes may not be fully representative.<ref name="pmid16929042">{{cite journal |author=McKibbon KA, Fridsma DB |title=Effectiveness of clinician-selected electronic information resources for answering primary care physicians' information needs |journal=JAMIA |volume=13 |pages=653–9 |year=2006 |pmid=16929042 |doi=10.1197/jamia.M2087}}</ref>


Regarding the conclusions reached in [[randomized controlled trial]]s, one study did not find evidence of overstatement<ref name="pmid10535436">{{cite journal |author=Friedberg M ''et al.'' |title=Evaluation of conflict of interest in economic analyses of new drugs used in oncology |journal=JAMA |volume=282 |pages=1453–7 |year=1999 |pmid=10535436 |doi=}}</ref>; however, a later study<ref name="pmid12928469">{{cite journal |author=Als-Nielsen B ''et al.''|title=Association of funding and conclusions in randomized drug trials: a reflection of treatment effect or adverse events? |journal=JAMA |volume=290 |pages=921–8 |year=2003 |pmid=12928469 |doi=10.1001/jama.290.7.921}}</ref> found that industry sponsored studies are more likely to recommend the experimental drug as treatment of choice even after adjusting for the treatment effect. Similarly, industry sponsored studies may be more likely to conclude that drugs are safe, even when they have increased adverse effects.<ref name="pmid17954797">{{cite journal |author=Nieto A ''et al.'' |title=Adverse effects of inhaled corticosteroids in funded and nonfunded studies |journal=Arch Intern Med |volume=167 |pages=2047–53 |year=2007 |pmid=17954797 |doi=10.1001/archinte.167.19.2047}}</ref>
Research conflicts on the ability of end-users of MEDLINE. One study found that users were almost as likely to misinterpret articles found as correctly interpret them.<ref name="pmid16929042"/> A second study that was in vitro found that searching for evidence was helpful.<ref name="pmid15684126">{{cite journal |author=Westbrook JI, Coiera EW, Gosling AS |title=Do online information retrieval systems help experienced clinicians answer clinical questions? |journal=J Am Med Inform Assoc |volume=12 |issue=3 |pages=315–21 |year=2005 |pmid=15684126 |doi=10.1197/jamia.M1717 |url=http://www.jamia.org/cgi/pmidlookup?view=long&pmid=15684126 |issn=}}</ref>


Unfortunately, the presence of authors with conflict of interests is not reliably indicated in journal articles.<ref name="pmid11405896">{{cite journal |author=Papanikolaou GN ''et al.''|title=Reporting of conflicts of interest in guidelines of preventive and therapeutic interventions |journal=BMC medical research methodology |volume=1  |pages=3 |year=2001 |pmid=11405896 |doi=}}</ref> In addition, when studied in the late 1990s, approximately 10% of some types of articles used 'ghost writers'.<ref name="pmid16230729">{{cite journal |author=Laine C, Mulrow CD |title=Exorcising ghosts and unwelcome guests |journal=Ann Intern. Med |volume=143  |pages=611–2 |year=2005 |pmid=16230729 |doi=|url=http://www.annals.org/cgi/content/full/143/8/611}}</ref> Ghost writers mean that the credited author in the byline may not have been the real author and the real author may have a conflict of interest.
One proposed structure for a comprehensive evidence search is the 5S search strategy,<ref name="pmid17080967"/> and 6S<ref name="pmid19755349">{{cite journal| author=DiCenso A, Bayley L, Haynes RB| title=ACP Journal Club. Editorial: Accessing preappraised evidence: fine-tuning the 5S model into a 6S model. | journal=Ann Intern Med | year= 2009 | volume= 151 | issue= 6 | pages= JC3-2, JC3-3 | pmid=19755349
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=19755349 }} [http://www.acpjc.org/Content/151/3/issue/ACPJC-2009-151-3-002.htm Full text from www.acpjc.org]<!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref> which starts with the search of "summaries" (textbooks). <ref name="pmid17082828">{{cite journal |author=Patel MR ''et al.'' |title=Randomized trial for answers to clinical questions: evaluating a pre-appraised versus a [[MEDLINE]] search protocol |journal= JMLA |volume=94 |pages=382–7 |year=2006 |pmid=17082828 |doi=}}</ref>


====Other issues====
===Appraisal of evidence===
Statistical analysis of the outcomes of a clinical trial is a complex and highly technical process. These often require the involvement of a professional medical statistician whose advice is needed in the design of the trial as well as in the analysis of its outcome. Flaws in the design of a trial can lead subsequently to weaknesses in statistical analysis. Ideally, a trial protocol should be carefully designed with statistical issues in mind, and with the hypothesis under test clearly formulated, and the agreed protocol should then be strictly adhered to. Often however problems arise during the test; for example, there may be unanticipated outcomes of the trial, or problems in patient recruitment or in compliance with the test protocol, and these problems can weaken the power and authority of the trial. Common problems include small sample sizes in some of the groups<ref name="pmid17975858">{{cite journal |author=Glasziou P, Doll H |title=Was the study big enough? Two "café" rules (Editorial) |journal=ACP J Club |volume=147  |pages=A08 |year=2007 |pmid=17975858 |doi=}}</ref>, problems of "multiple comparisons" when several different outcomes are being assessed, and biasing of study populations by selection criteria.
<!-- Start of USPSTF text box -->
{|align="right" cellpadding="10" style="background-color:#FFFFCC; width:50%; border: 1px solid #aaa; margin:20px; font-size: 92%;"
|
The [[U.S. Preventive Services Task Force]] (USPSTF) <ref>U.S. Preventive Services Task Force Ratings: [[http://www.ahrq.gov/clinic/3rduspstf/ratings.htm  Strength of Recommendations and Quality of Evidence. Guide to Clinical Preventive Services], Third Edition: Periodic Updates, 2000-2003. Hosted by Agency for Healthcare Research and Quality, Rockville, MD.</ref> grades its recommendations for treatments according to the strength of the evidence and the expected overall benefit (benefits minus harms). Its grades are:


===Apply===
A.— Good evidence that the treatment improves health outcomes, and benefits substantially outweigh harms.
It is important to "'''apply'''" correctly the answers found. Common problems in applying evidence are 1) difficulties with numeracy and 2) recognition of the correct population that evidence applies to.


====Difficulties with health numeracy====
B.— Fair evidence that the treatment improves health outcomes and that benefits outweigh harms.
Both patients and healthcare professionals have difficulties with health numeracy and probabilistic reasoning.<ref name="pmid17712082">{{cite journal |author=Ancker JS, Kaufman D |title=Rethinking Health Numeracy: A Multidisciplinary Literature Review |journal= |volume=  |pages= |year=2007 |pmid=17712082 |doi=10.1197/jamia.M2464}}</ref>


====Difficulties in applying evidence to the correct patient population====
C.— Fair evidence that the treatment can improve health outcomes but the balance of benefits and harms is too close to justify a general recommendation.
Studies document that extrapolating study results to the wrong patient populations (over-generalization)<ref name="pmid11147985">{{cite journal |author=Gross CP ''et al.'' |title=Relation between prepublication release of clinical trial results and the practice of carotid endarterectomy |journal=JAMA |volume=284 |pages=2886–93 |year=2000 |pmid=11147985 |doi= |issn=}}</ref><ref name="pmid15295047">{{cite journal |author=Juurlink DN ''et al.'' |title=Rates of hyperkalemia after publication of the Randomized Aldactone Evaluation Study |journal=N Engl J Med |volume=351  |pages=543–51 |year=2004 |pmid=15295047 |doi=10.1056/NEJMoa040135 |issn=}}</ref><ref name="pmid17488964">{{cite journal |author=Beohar N ''et al.'' |title=Outcomes and complications associated with off-label and untested use of drug-eluting stents |journal=JAMA |volume=297|pages=1992–2000 |year=2007 |pmid=17488964 |doi=10.1001/jama.297.18.1992 |issn=}}</ref> and not applying study results to the correct population (under-utilization)<ref name="pmid8990335">{{cite journal |author=Soumerai SB ''et al.'' |title=Adverse outcomes of underuse of beta-blockers in elderly survivors of acute myocardial infarction |journal=JAMA |volume=277 |pages=115–21 |year=1997 |pmid=8990335 |doi=}}</ref><ref name="pmid11228280">{{cite journal |author=Hemingway H ''et al.'' |title=Underuse of coronary revascularization procedures in patients considered appropriate candidates for revascularization |journal=N Engl J Med |volume=344 |pages=645–54 |year=2001 |pmid=11228280 |doi=}}</ref> can both increase adverse outcomes.


'''Over-generalization'''<br>
D.— Recommendation against routinely providing the treatment to asymptomatic patients. There is fair evidence that [the service] is ineffective or that harms outweigh benefits.
The problem in over-generalization of study results may be more common among specialist physicians.<ref name="pmid11422641">{{cite journal |author=Turner BJ, Laine C |title=Differences between generalists and specialists: knowledge, realism, or primum non nocere? |journal=J Gen Intern Med |volume=16  |pages=422-4 |year=2001 |pmid=11422641 |doi=10.1046/j.1525-1497.2001.016006422.x}} [http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=wikipedia&pubmedid=11422641 PubMed Central]</ref> Two studies found specialists were more likely to adopt COX-2 drugs before the drugs were recalled by the FDA <ref name="pmid15755796">{{cite journal |author=Rawson N ''et al.'' |title=Factors associated with celecoxib and rofecoxib utilization |journal=Ann Pharmacother |volume=39 |pages=597-602 |year=2005 |pmid=15755796}}</ref><ref name="pmid16808768">{{cite journal |author=De Smet BD ''et al.'' |title=Over and under-utilization of cyclooxygenase-2 selective inhibitors by primary care physicians and specialists: the tortoise and the hare revisited |journal=J Gen Intern Med |volume=21 |pages=694-7 |year=2006 |pmid=16808768 |doi=10.1111/j.1525-1497.2006.00463.x}}</ref>. One of the studies went on to state "using COX-2s as a model for physician adoption of new therapeutic agents, specialists were more likely to use these new medications for patients likely to benefit but were also significantly more likely to use them for patients without a clear indication".<ref name="pmid16808768"/> Similarly, orthopedists may provide more intensive care for back pain, but without benefit from the increased care.<ref name="pmid7666878">{{cite journal | author = Carey T ''et al.''| title = The outcomes and costs of care for acute low back pain among patients seen by primary care practitioners, chiropractors, and orthopedic surgeons. The North Carolina Back Pain Project | journal = N Engl J Med | volume = 333 |pages = 913-7 | year = 1995 | id = PMID 7666878}}</ref> Specialists may be less discriminating in their choice of journal reading. <ref name="pmid17641754">{{cite journal |author=McKibbon KA ''et al.'' |title=Which journals do primary care physicians and specialists access from an online service? |journal= JMLA |volume=95 |pages=246-54 |year=2007 |pmid=17641754 |doi=10.3163/1536-5050.95.3.246}}</ref>


'''Under-utilization'''<br>
I.— The evidence is insufficient to recommend for or against routinely providing [the service]. Evidence that the treatment is effective is lacking, of poor quality, or conflicting and the balance of benefits and harms cannot be determined.
The problem of under-utilizing study results may be more common when physicians are practicing outside of their expertise. For example, specialist physicians are less likely to under-utilize specialty care<ref name="pmid11422631">{{cite journal | author = Majumdar S ''et al.'' | title = Influence of physician specialty on adoption and relinquishment of calcium channel blockers and other treatments for myocardial infarction | journal = J Gen Intern Med | volume = 16 |  pages = 351-9 | year = 2001 | id = PMID 11422631}}</ref><ref name="pmid8759658">{{cite journal | author = Fendrick A, Hirth R, Chernew M | title = Differences between generalist and specialist physicians regarding Helicobacter pylori and peptic ulcer disease | journal = Am J Gastroenterol | volume = 91 | pages = 1544-8 | year = 1996 | id = PMID 8759658}}</ref>, while primary care physicians are less likely to under-utilize  preventive care<ref name="pmid1983933">{{cite journal | author = Lewis C ''et al.'' | title = The counseling practices of internists | journal = Ann Intern Med | volume = 114 | pages = 54-8 | year = 1991 | id = PMID 1983933}}</ref><ref name="pmid1599724">{{cite journal | author = Turner B ''et al.'' | title = Breast cancer screening: effect of physician specialty, practice setting, year of medical school graduation, and sex | journal = Am J Prev Med | volume = 8 |  pages = 78-85 | year = | id = PMID 1599724}}</ref>.


===Assess===
The USPSTF also grades the quality of the overall evidence as good, fair or poor:
To evaluate one's performance.


==Classification==
''Good'': Evidence includes consistent results from well-designed, well-conducted studies in representative populations that directly assess effects on health.
Two types of evidence-based medicine have been proposed.<ref name="pmid15647211">{{cite journal |author=Eddy DM |title=Evidence-based medicine: a unified approach |journal=Health affairs (Project Hope) |volume=24 |pages=9-17 |year=2005 |pmid=15647211 |doi=10.1377/hlthaff.24.1.9}}</ref>
===Evidence-based guidelines===
Evidence-based guidelines (EBG) is the practice of evidence-based medicine at the ''organizational or institutional'' level. This includes the production of guidelines, policy, and regulations.
===Evidence-based individual decision making===
Evidence-based individual decision (EBID) making is evidence-based medicine as practiced by the ''individual [[health care provider]] and an individual patient''. There is concern that current evidence-based medicine focuses excessively on EBID.<ref name="pmid15647211"/>


Evidence-based individual decision making can be further divided into three modes, "doer", "user", "replicator" by the intensity of the work by the individual.<ref name="pmid11033714">{{cite journal |author=Straus SE, McAlister FA |title=Evidence-based medicine: a commentary on common criticisms |journal=CMAJ : Canadian Medical Association Journal |volume=163 |pages=837–41 |year=2000 |pmid=11033714 |doi=}}</ref>
''Fair'': Evidence is sufficient to determine effects on health outcomes, but its strength is limited by the number, quality, or consistency of the individual studies, generalizability to routine practice, or indirect nature of the evidence on health outcomes.


This categorization somewhat parallels the theory of [[Diffusion of innovations]], but without pejorative terms, in which adopters of innovation are categorized as innovators (2.5%), early adopters (13%), early majority (33%), late majority (33%), and laggards (16%).<ref name="pmid12697800">{{cite journal |author=Berwick DM |title=Disseminating innovations in health care |journal=JAMA |volume=289 |pages=1969–75 |year=2003 |pmid=12697800 |doi=10.1001/jama.289.15.1969 |issn=}}</ref> This categorization for doctors is supported by a preliminary empirical study of Green et al. that grouped doctors into Seekers, Receptives, Traditionalists, and Pragmatists.<ref name="pmid12485547">{{cite journal |author=Green LA, Gorenflo DW, Wyszewianski L |title=Validating an instrument for selecting interventions to change physician practice patterns: a Michigan Consortium for Family Practice Research study |journal=Journal of Family Practice |volume=51  |pages=938–42 |year=2002 |pmid=12485547 |doi=|url=http://www.jfponline.com/Pages.asp?AID=1332}}</ref> The study of Green ''et al.'' has not been externally validated.
''Poor'': Evidence is insufficient to assess the effects on health outcomes because of limited number or power of studies, flaws in their design or conduct, gaps in the chain of evidence, or lack of information on important health outcomes.
|}
<!-- End of USPSTF text box -->


The same doctors may vary which group they resemble depending on how much time is available to seek evidence during clinical care.<ref name="pmid12058546">{{cite journal |author=Montori VM ''et al.'' |title=A qualitative assessment of 1st-year internal medicine residents' perceptions of evidence-based clinical decision making |journal=Teaching and Learning in Medicine |volume=14 |pages=114–8 |year=2002 |pmid=12058546 |doi=}}</ref> Medicine residents early in training tend to prefer being taught the practitioner model, whereas residents later in training tended to prefer the user model.<ref name="pmid16707306">{{cite journal |author=Akl EA ''et al.''|title=EBM user and practitioner models for graduate medical education: what do residents prefer? |journal=Medical Teacher |volume=28 |pages=192–4 |year=2006 |pmid=16707306 |doi=10.1080/01421590500314207}}</ref>
To "'''Appraise'''" the quality of the evidence in a study is very important, as one third of the results of even the most visible medical research is eventually either attenuated or refuted.<ref name="pmid16014596"/> There are many reasons for this<ref name="pmid9546568">{{cite journal |author=Ioannidis JP ''et al.''|title=Issues in comparisons between meta-analyses and large trials |journal=JAMA |volume=279 |pages=1089–93 |year=1998 |pmid=9546568 |doi=}}</ref>; two of the most common being ''[[publication bias]]''<ref name="pmid1727960">{{cite journal |author=Dickersin K ''et al.'' |title=Factors influencing publication of research results. Follow-up of applications submitted to two institutional review boards |journal=JAMA |volume=267 |pages=374–8 |year=1992 |pmid=1727960 |doi=}}</ref> and ''[[conflict of interest]]''<ref name="pmid15916457">{{cite journal |author=Smith R |title=Medical journals are an extension of the marketing arm of pharmaceutical companies |journal=PLoS Med |volume=2  |pages=e138 |year=2005 |pmid=15916457 |doi=10.1371/journal.pmed.0020138}}</ref> (see article on [[Medical ethics]]). These two problems interact, as [[conflict of interest]] often leads to [[publication bias]].<ref name="pmid12775615">{{cite journal |author=Melander H ''et al.'' |title=Evidence b(i)ased medicine--selective reporting from studies sponsored by pharmaceutical industry: review of studies in new drug applications |journal=BMJ |volume=326 |pages=1171–3 |year=2003 |pmid=12775615 |doi=10.1136/bmj.326.7400.1171}}</ref><ref name="pmid1727960"/> Complicating the appraisal process further, many (if not all) studies contain  some design flaws, and even when there are no clear methodological flaws, any outcome of a test that is evaluated by ''statistical test'' has a margin of error: this means that some positive outcomes will be "false positives".


====Doer====
Often, only the abstract of an article will be read,<ref name="pmid11119185">{{cite journal |author=Saint S ''et al'' |title=Journal reading habits of internists |journal=J Gen Intern Med |volume=15  |pages=881–4 |year=2000 |pmid=11119185 |doi=}}</ref> but many abstracts contain errors.<ref name="pmid10188662">{{cite journal |author=Pitkin RM ''et al.''|title=Accuracy of data in abstracts of published research articles |journal=JAMA |volume=281|pages=1110–1 |year=1999 |pmid=10188662 |doi=}}</ref> These are usually errors of omission rather than contradiction, but abstracts often over-emphasise positive findings and neglect to mention limitations.  
The "''doer''"<ref name="pmid11033714"/> or "''practitioner''"<ref name="pmid10753130">{{cite journal |author=Guyatt GH ''et al.''|title=Practitioners of evidence based care. Not all clinicians need to appraise evidence from scratch, but all need some skills |journal=BMJ |volume=320 |pages=954–5 |year=2000 |pmid=10753130 |doi=}}</ref> of evidence-based medicine does at least the first four steps (above) of evidence-based medicine and are performed for "''self-acquired''"<ref name="pmid12058546"/> knowledge.


If the Doers are the same as the "''Seekers''" in the study of Green, then this group may be 3% of physicians.<ref name="pmid12485547"/>
When abstracts are read, readers may be biased <ref>Lord, Charles, Ross, Lee, and Lepper, Mark (1979). '[http://www.psych.umn.edu/courses/spring07/borgidae/psy5202/readings/lord,%20ross%20&%20lepper%20(1979).pdf Biased Assimilation and Attitude Polarization: The Effects of Prior Theories on Subsequently Considered Evidence]',Journal of Personality and Social Psychology, 37 (11): 2098-2109. </ref> and make illogical conclusions<ref name="pmid3701813">{{cite journal |author=Bergman DA, Pantell RH |title=The impact of reading a clinical study on treatment decisions of physicians and residents |journal=J Med Educ |volume=61 |issue=5 |pages=380–6 |year=1986 |month=May |pmid=3701813 |doi= |url= |issn=}}</ref>.


This group may also be the similarly small group of doctors who use formal [[Bayesian calculations]]<ref name="pmid9576412">{{cite journal |author=Reid MC ''et al.''|title=Academic calculations versus clinical judgments: practicing physicians' use of quantitative measures of test accuracy |journal=Am J Med |volume=104|pages=374–80 |year=1998 |pmid=9576412 |doi=}}</ref> or [[MEDLINE]] searches<ref name="pmid10435959">{{cite journal |author=Ely JW ''et al.'' |title=Analysis of questions asked by family doctors regarding patient care |journal=BMJ |volume=319 |pages=358–61 |year=1999 |pmid=10435959 |doi=}}[http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=10435959 PubMed Central]</ref>.
The initial steps in reading an article are determining what the article's conclusion and whether its conclusion, if valid, is important.<ref name="pmid7471000">{{cite journal| author=| title=How to read clinical journals: I. why to read them and how to start reading them critically. | journal=Can Med Assoc J | year= 1981 | volume= 124 | issue= 5 | pages= 555-8 | pmid=7471000 | doi= | pmc=PMC1705173 | url= }} </ref>


====User====
Overall risk in the population in a study can be assessed by examining outcome rr prevalence rates in the control groups.<ref name="pmid16613605">{{cite journal| author=Hayward RA, Kent DM, Vijan S, Hofer TP| title=Multivariable risk prediction can greatly enhance the statistical power of clinical trial subgroup analysis. | journal=BMC Med Res Methodol | year= 2006 | volume= 6 | issue=  | pages= 18 | pmid=16613605 | doi=10.1186/1471-2288-6-18 | pmc=PMC1523355 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16613605  }} </ref>
For the "''user''" of evidence-based medicine, ''[literature]'' searches are restricted to evidence sources that have already undergone critical appraisal by others, such as evidence-based guidelines or evidence summaries"<ref name="pmid11033714"/>. More recently, the 5S search strategy,<ref name="pmid17080967"/>  which starts with the search of "summaries" (evidence-based textbooks) is a quicker approach.<ref name="pmid17082828"/>


If the Users are the same as the "''Receptives''" in the study of Green, then this group may be 57% of physicians.<ref name="pmid12485547"/>
Automated text mining can help assess the quality of an article.<ref name="pmid21707873">{{cite journal| author=Lin JW, Chang CH, Lin MW, Ebell MH, Chiang JH| title=Automating the process of critical appraisal and assessing the strength of evidence with information extraction technology. | journal=J Eval Clin Pract | year= 2011 | volume=  | issue=  | pages=  | pmid=21707873 | doi=10.1111/j.1365-2753.2011.01712.x | pmc= | url= }} </ref>


====Replicator====
"Levels of evidence" are used for describing the strength of a research study.<ref name="pmid115569">{{cite journal| author=| title=The periodic health examination. Canadian Task Force on the Periodic Health Examination. | journal=Can Med Assoc J | year= 1979 | volume= 121 | issue= 9 | pages= 1193-254 | pmid=115569
For the "''replicator''", "decisions of respected opinion leaders are followed"<ref name="pmid11033714"/>. This has been called "'''borrowed' expertise''".<ref name="pmid12058546"/>
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=115569 | pmc=PMC1704686 }}</ref><ref name="titleLevels of Evidence">{{cite web |url=http://www.eboncall.org/content/levels.html |title=Levels of Evidence |accessdate=2007-12-31 |author= |authorlink= |coauthors= |date= |format= |work= |publisher= |pages= |language= |archiveurl= |archivedate= |quote=}}</ref> The [http://www.equator-network.org/ Equator network] is a collection of standards to improve the reporting of health research. An example is the [http://www.consort-statement.org/ Consort statement] for the reporting of randomized controlled trials.


If the Replicators are the same as the "''Traditionalists''" and "''Pragmatists''" combined in the study of Green, then this group may be 40% of physicians.<ref name="pmid12485547"/> This is a very broad group of doctors. Possibly the lowest end of this group may be equivalent to the laggards of Rogers. This much smaller group of doctors, ones who have "severely diminished capacity for self-improvement", may be at increased risk of disciplinary action by medical boards.<ref name="pmid16371633">{{cite journal |author=Papadakis MA ''et al.'' |title=Disciplinary action by medical boards and prior behavior in medical school |journal=N Engl J Med |volume=353 |pages=2673–82 |year=2005 |pmid=16371633 |doi=10.1056/NEJMsa052596 |issn=}}</ref>
Guides exist for assessing a body of literature; these are discussed below, [[Evidence-based medicine#Assessing a body of research evidence|Assessing a body of research evidence]].


==Metrics used in evidence-based medicine==
;Common threats to validity
===Diagnosis===
'''Publication bias''' <br/>
* Sensitivity and specificity
[[Publication bias]] is "the influence of study results on the chances of publication [in [[academic journal]]s] and the tendency of investigators, reviewers, and editors to submit or accept manuscripts for publication based on the direction or strength of the study findings. Publication bias has an impact on the interpretation of clinical trials and meta-analyses. Bias can be minimized by insistence by editors on high-quality research, thorough literature reviews, acknowledgment of conflicts of interest, modification of peer review practices, etc."<ref name="title">{{cite web |url=http://www.nlm.nih.gov/cgi/mesh/2007/MB_cgi?term=publication+bias |title=Publication bias |accessdate=2007-12-17 |author=National Library of Medicine |authorlink= |coauthors= |date= |format= |work= |publisher= |pages= |language= |archiveurl= |archivedate= |quote=}}</ref>
* Likelihood ratios ([[Odds ratio]]s)


===Interventions===
'''Conflict of interest'''<br/>
====Relative measures====
{{main|Conflict of interest}}
* Relative risk ratio
The presence of a conflict of interest has many effects in medical publishing.
* Relative risk reduction


====Absolute measures====
'''Statistical analysis'''<br/>
* Absolute risk reduction
Common problems include small sample sizes in subgroup analyses<ref name="pmid17975858">{{cite journal |author=Glasziou P, Doll H |title=Was the study big enough? Two "café" rules (Editorial) |journal=ACP J Club |volume=147  |pages=A08 |year=2007 |pmid=17975858 |doi=}}</ref>, problems of "multiple comparisons" when several outcomes are being assessed, and biasing of study populations by selection criteria.
* Number needed to treat
* Number needed to screen
* Number needed to harm


===Health policy===
Problems may arise from interim analyses of [[randomized controlled trial]]s which may lead to exaggerated estimations of treatment effects.<ref name="pmid16264162">{{cite journal |author=Montori VM ''et al'' |title=Randomized trials stopped early for benefit: a systematic review |journal=JAMA |volume=294  |pages=2203–9 |year=2005 |month=November |pmid=16264162 |doi=10.1001/jama.294.17.2203 |url=http://jama.ama-assn.org/cgi/pmidlookup?view=long&pmid=16264162 |issn=}}</ref><ref>Trotta, F ''et al.'' (2008) Stopping a trial early in oncology: for patients or for industry? Ann Oncol mdn042. http://dx.doi.org/10.1093/annonc/mdn042</ref> <ref name="pmid15014189">{{cite journal |author=Slutsky AS, Lavery JV |title=Data Safety and Monitoring Boards |journal=N Engl J Med |volume=350 |pages=1143–7 |year=2004 |pmid=15014189 |doi=10.1056/NEJMsb033476 |url=http://content.nejm.org/cgi/pmidlookup?view=short&pmid=15014189&promo=ONFLNS19 |issn=}}</ref>
* Cost per year of life saved<ref name="pmid7604170">{{cite journal |author=Tengs TO ''et al'' |title=Five-hundred life-saving interventions and their cost-effectiveness |journal=Risk Anal |volume=15 |pages=369–90 |year=1995 |pmid=7604170 |doi=}}</ref>
* Years (or months or days) of life saved. "A gain in life expectancy of a month from a preventive intervention  targeted at populations at average risk and a gain of a year  from a preventive intervention targeted at populations at elevated  risk can both be considered large."<ref name="pmid9691106">{{cite journal |author=Wright JC, Weinstein MC |title=Gains in life expectancy from medical interventions--standardizing data on outcomes |journal=N Engl J Med |volume=339 |pages=380–6 |year=1998 |pmid=9691106 |doi=}}</ref>


===Statistical significance===
Statistical significance:<br/>
The p-value expresses the likelihood that a null hypothesis is true.<ref name="pmid10383371">{{cite journal |author=Goodman SN |title=Toward evidence-based medical statistics. 1: The P value fallacy |journal=Ann. Intern. Med. |volume=130 |issue=12 |pages=995–1004 |year=1999 |pmid=10383371 |doi=|url=http://www.annals.org/cgi/content/full/130/12/995}}</ref> However, the p-value should be interpreted in light of how plausible is the hypothesis based on prior research and physiologic knowledge.<ref name="pmid3573245">{{cite journal |author=Browner WS, Newman TB |title=Are all significant P values created equal? The analogy between diagnostic tests and clinical research |journal=JAMA |volume=257 |issue=18 |pages=2459–63 |year=1987 |pmid=3573245 |doi=}}</ref><ref name="pmid10383371"/><ref name="pmid10383350">{{cite journal |author=Goodman SN |title=Toward evidence-based medical statistics. 2: The Bayes factor |journal=Ann. Intern. Med. |volume=130 |issue=12 |pages=1005–13 |year=1999 |pmid=10383350 |doi=|url=http://www.annals.org/cgi/content/full/130/12/1005}}</ref>
The [[statistical significance]] of the outcome of a study is often summarized by a "P-value" that expresses the likelihood that an observed difference between treatment groups reflects a true difference in treatment effect; the P value is a calculation of the chance that the observed difference reflects the chance outcome of random sampling. Some have argued that focusing on P values neglects other important sources of knowledge and information that should be used to assess the likely efficacy of a treatment <ref name="pmid10383371">{{cite journal |author=Goodman SN |title=Toward evidence-based medical statistics. 1: The P value fallacy |journal=Ann Intern Med |volume=130 |pages=995–1004 |year=1999 |pmid=10383371 |doi=|url=http://www.annals.org/cgi/content/full/130/12/995}}</ref> In particular, some argue that the P-value should be interpreted in light of how plausible is the hypothesis based on the totality of prior research and physiologic knowledge.<ref name="pmid3573245">{{cite journal |author=Browner WS, Newman TB |title=Are all significant P values created equal? The analogy between diagnostic tests and clinical research |journal=JAMA |volume=257 |pages=2459–63 |year=1987 |pmid=3573245 |doi=}}</ref><ref name="pmid10383371"/><ref name="pmid10383350">{{cite journal |author=Goodman SN |title=Toward evidence-based medical statistics. 2: The Bayes factor |journal=Ann Intern Med |volume=130 |pages=1005–13 |year=1999 |pmid=10383350 |doi=|url=http://www.annals.org/cgi/content/full/130/12/1005}}</ref> Bayesian inference formalizes this approach to [[statistical significance]].


==Experimental trials: producing the evidence==
===Application===
{{main|Randomized controlled trial}}
It is important to "'''apply'''" the best practices found to the correct situation. One common problem in applying evidence is that both patients and healthcare professionals often have difficulties with [[quantitative literacy|health numeracy]] and probabilistic reasoning.<ref name="pmid17712082">{{cite journal |author=Ancker JS, Kaufman D |title=Rethinking health numeracy: a multidisciplinary literature review |journal= |volume=  |pages= |year=2007 |pmid=17712082 |doi=10.1197/jamia.M2464}}</ref> Another problem is successful clinical reasoning at the bedside.<ref name="pmid3736379">{{cite journal |author=Dubeau CE ''et al.''|title=Premature conclusions in the diagnosis of iron-deficiency anemia: cause and effect |journal=Med Decis Making |volume=6  |pages=169–73 |year=1986 |pmid=3736379 |doi=}}</ref> Successful reasoning is associated with the use of pattern matching <ref name="pmid12895249">{{cite journal |author=Coderre S ''et al.'' |title=Diagnostic reasoning strategies and diagnostic success |journal=Med Educ |volume=37  |pages=695–703 |year=2003 |pmid=12895249 |doi=}}</ref><ref name="pmid7070446">{{cite journal |author=Eddy DM, Clanton CH |title=The art of diagnosis: solving the clinicopathological exercise |journal=N Engl J Med |volume=306  |pages=1263–8 |year=1982 |pmid=7070446 |doi=}}</ref> and recognizing clinical findings that are "pivot" or specific to certain diseases<ref name="pmid7070446"/>. A third problem is to identify exactly which patients will benefit from the new practices. Extrapolating study results to the wrong patient populations (over-generalization)<ref name="pmid11147985">{{cite journal |author=Gross CP ''et al.'' |title=Relation between prepublication release of clinical trial results and the practice of carotid endarterectomy |journal=JAMA |volume=284 |pages=2886–93 |year=2000 |pmid=11147985 |doi= |issn=}}</ref><ref name="pmid15295047">{{cite journal |author=Juurlink DN ''et al.'' |title=Rates of hyperkalemia after publication of the Randomized Aldactone Evaluation Study |journal=N Engl J Med |volume=351  |pages=543–51 |year=2004 |pmid=15295047 |doi=10.1056/NEJMoa040135 |issn=}}</ref><ref name="pmid17488964">{{cite journal |author=Beohar N ''et al.'' |title=Outcomes and complications associated with off-label and untested use of drug-eluting stents |journal=JAMA |volume=297|pages=1992–2000 |year=2007 |pmid=17488964 |doi=10.1001/jama.297.18.1992 |issn=}}</ref> and not applying study results to the correct population (under-utilization)<ref name="pmid8990335">{{cite journal |author=Soumerai SB ''et al.'' |title=Adverse outcomes of underuse of beta-blockers in elderly survivors of acute myocardial infarction |journal=JAMA |volume=277 |pages=115–21 |year=1997 |pmid=8990335 |doi=}}</ref><ref name="pmid11228280">{{cite journal |author=Hemingway H ''et al.'' |title=Underuse of coronary revascularization procedures in patients considered appropriate candidates for revascularization |journal=N Engl J Med |volume=344 |pages=645–54 |year=2001 |pmid=11228280 |doi=}}</ref> can both increase adverse outcomes.
"A clinical trial is defined as a prospective scientific experiment that involves human subjects in whom treatment is initiated for the evaluation of a therapeutic intervention. In a randomized controlled clinical trial, each patient is assigned to receive a specific treatment intervention by a chance mechanism."<ref name="pmid17339574">{{cite journal |author=Stanley K |title=Design of randomized controlled trials |journal=Circulation |volume=115 |issue=9 |pages=1164–9 |year=2007 |pmid=17339574 |doi=10.1161/CIRCULATIONAHA.105.594945}}</ref> The theory behind these trials is that the value of a treatment will be shown in an objective way, and, though usually unstated, there is an assumption that the results of the trial will be applicable to the care of patients who have the condition that was treated.


The best evidence is thought to come from large multicentre clinical trials that are randomised and placebo-controlled, and which are conducted double-blind according to a predetermined schedule that is strictly adhered to. Trials should be large, so that serious adverse events might be detected even when they occur rarely. Multi-centre trials minimise problems that can arise when a single geographical locus has a population that is not fully representative of the global population, and they can minimise the effect of geographical variations in environmenet and health care delivery. Randomisation (if the study population is large enough) should mean that the study groups are unbiased. A double-blind trial is one in which neither the patient nor the deliverer of the treatment is aware of the nature of the treatment offered to any particular individual, and this avoids bias caused by the expectations of either the doctor or the patient. Placebo controls are important, because the [[placebo effect]] can often be very strong.
The problem of over-generalizating study results may be more common among specialist physicians.<ref name="pmid11422641">{{cite journal |author=Turner BJ, Laine C |title=Differences between generalists and specialists: knowledge, realism, or primum non nocere? |journal=J Gen Intern Med |volume=16  |pages=422-4 |year=2001 |pmid=11422641 |doi=10.1046/j.1525-1497.2001.016006422.x}} [http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=wikipedia&pubmedid=11422641 PubMed Central]</ref> Two studies found specialists were more likely to adopt [[cyclooxygenase 2 inhibitors|cyclooxygenase 2 inhibitor]] drugs before the drug [[rofecoxib]] was withdrawn by its manufacturers because of its unanticipated adverse effects <ref name="pmid15755796">{{cite journal |author=Rawson N ''et al.'' |title=Factors associated with celecoxib and rofecoxib utilization |journal=Ann Pharmacother |volume=39 |pages=597-602 |year=2005 |pmid=15755796}}</ref><ref name="pmid16808768">{{cite journal |author=De Smet BD ''et al.'' |title=Over and under-utilization of cyclooxygenase-2 selective inhibitors by primary care physicians and specialists: the tortoise and the hare revisited |journal=J Gen Intern Med |volume=21 |pages=694-7 |year=2006 |pmid=16808768 |doi=10.1111/j.1525-1497.2006.00463.x}}</ref>. One of the studies went on to state:
::"''using COX-2s as a model for physician adoption of new therapeutic agents, specialists were more likely to use these new medications for patients likely to benefit but were also significantly more likely to use them for patients without a clear indication''".<ref name="pmid16808768"/>
Similarly, orthopedists provide more expensive care for back pain, but without measurably increased benefit compared to other types of practitioners.<ref name="pmid7666878">{{cite journal | author = Carey T ''et al.''| title = The outcomes and costs of care for acute low back pain among patients seen by primary care practitioners, chiropractors, and orthopedic surgeons. The North Carolina Back Pain Project | journal = N Engl J Med | volume = 333 |pages = 913-7 | year = 1995 | id = PMID 7666878}}</ref>  Some of the reason that subspecialists may be more likely to adopt inadequately studied innovations is that they read from a spectrum of [[academic journal|journals]] that have less consistent quality.<ref name="pmid17641754">{{cite journal |author=McKibbon KA ''et al.'' |title=Which journals do primary care physicians and specialists access from an online service? |journal= JMLA |volume=95 |pages=246-54 |year=2007 |pmid=17641754 |doi=10.3163/1536-5050.95.3.246}}</ref> Articles from specialty [[academic journal|journals]] have been noted to persist in supporting claims in the medical literature that have been refuted.<ref name=pmidpending_Tatsioni">Tatsioni A, Bonitsis NG, Ioannidis JPA (2007) Persistence of contradicted claims in the literature. ''JAMA'' [http://jama.ama-assn.org/cgi/content/abstract/298/21/2517 298]</ref>


However such trials are very expensive, difficult to co-ordinate properly, and are often impracal to design optimally. For example, for many types of medical intervention, no satisfactory placebo treatment is possible.
The problem of under-utilizing study results may be more common when physicians are practising outside their expertise. For example, specialist physicians are less likely to under-utilize specialty care<ref name="pmid11422631">{{cite journal | author = Majumdar S ''et al.'' | title = Influence of physician specialty on adoption and relinquishment of calcium channel blockers and other treatments for myocardial infarction | journal = J Gen Intern Med | volume = 16 |  pages = 351-9 | year = 2001 | id = PMID 11422631}}</ref><ref name="pmid8759658">{{cite journal | author = Fendrick A ''et al.'' | title = Differences between generalist and specialist physicians regarding Helicobacter pylori and peptic ulcer disease | journal = Am J Gastroenterol | volume = 91 | pages = 1544-8 | year = 1996 | id = PMID 8759658}}</ref>, while primary care physicians are less likely to under-utilize  preventive care<ref name="pmid1983933">{{cite journal | author = Lewis C ''et al.'' | title = The counseling practices of internists | journal = Ann Intern Med | volume = 114 | pages = 54-8 | year = 1991 | id = PMID 1983933}}</ref><ref name="pmid1599724">{{cite journal | author = Turner B ''et al.'' | title = Breast cancer screening: effect of physician specialty, practice setting, year of medical school graduation, and sex | journal = Am J Prev Med | volume = 8 |  pages = 78-85 | year = | id = PMID 1599724}}</ref>.


==Evidence synthesis: summarizing the evidence==
==Metrics used in EBM==
===Systematic review===
:'''Diagnosis'''
{{main|Systematic review}}
*  [[Sensitivity and specificity]]
A systematic review is a summary of healthcare research that involves a thorough literature search and critical appraisal of individual studies to identify the valid and applicable evidence. It often, but not always, uses appropriate techniques ([[meta-analysis]]) to combine these valid studies, and may grade the quality of the particular pieces of evidence according to the methodology used, and according to strengths or weaknesses of thstudy design.
*  [[Likelihood ratio]]s


While many systematic reviews are based on an explicit [[quantitative research|quantitative]] [[meta-analysis]] of available data, there are also [[qualitative research|qualitative]] reviews which nonetheless adhere to the standards for gathering, analyzing and reporting evidence.
:'''Causation'''
::''Relative measures''
*  [[Odds ratio]]
*  Relative risk ratio
*  [[Relative risk reduction]]


===Clinical practice guidelines===
::''Absolute measures''
{{main|Clinical practice guideline}}
*  [[Absolute risk reduction]]
Clinical practice guidelines are defined as "Directions or principles presenting current or future rules of policy for assisting health care practitioners in patient care decisions regarding diagnosis, therapy, or related clinical circumstances. The guidelines may be developed by government agencies at any level, institutions, professional societies, governing boards, or by the convening of expert panels. The guidelines form a basis for the evaluation of all aspects of health care and delivery."<ref>{{cite web |url=http://www.nlm.nih.gov/cgi/mesh/2007/MB_cgi?mode=&term=practice+guidelines |title=Clinical practice guidelines|author=National Library of Medicine |accessdate=2007-10-19 |format= |work=}}</ref>
*  [[Number needed to treat]] (NNT)<ref name="pmid3374545">{{cite journal |author=Laupacis A ''et al.'' |title=An assessment of clinically useful measures of the consequences of treatment |journal=N Engl J Med |volume=318 |pages=1728–33 |year=1988 |pmid=3374545 |doi=}}</ref>
*  [[Number needed to screen]]<ref name="pmid9685274">{{cite journal |author=Rembold CM |title=Number needed to screen: development of a statistic for disease screening |journal=BMJ |volume=317 |pages=307–12 |year=1998 |pmid=9685274 |doi= |issn=|url=http://www.bmj.com/cgi/content/full/317/7154/307}}</ref>
*  [[Number needed to harm]]


==Incorporating evidence into clinical care==
:'''Health policy''' {{main|Cost-benefit analysis}}
Practicing clinicians usually cite the lack of time for reading newer textbooks or journals. However, the emergence of new types of evidence can change the way doctors treat patients. Unfortunately the recent scientific evidence gathered through well controlled [[clinical trial]]s usually do not reach the busy clinicians in real time. Another potential problem lies in the fact that there may be numerous trials on similar interventions and outcomes but they are not [[systematic review|systematically reviewed]] or [[meta analysis|meta-analyzed]].
*  Cost per year of life saved<ref name="pmid7604170">{{cite journal |author=Tengs TO ''et al'' |title=Five-hundred life-saving interventions and their cost-effectiveness |journal=Risk Anal |volume=15 |pages=369–90 |year=1995 |pmid=7604170 |doi=}}</ref>
*  Cost of Preventing an Event (COPE)<ref name="pmid18170986">{{cite journal |author=Maharaj R |title=Adding cost to NNT: the COPE statistic |journal=ACP J. Club |volume=148 |pages=A8 |year=2008 |pmid=18170986 |doi= |issn=|url=http://www.acpjc.org/Content/148/1/issue/ACPJC-2008-148-1-A08.htm}}</ref>. For example, to prevent a major vascular event n a high-risk adult , the [[number needed to treat]] is 19, the number of years of treatment are 5, and the daily cost of the generic drug is 68 cents. The COPE is 19 * 5 * ( 365 * .68) which equals $23,579 in the United States.
*  Years (or months or days) of life saved. "A gain in life expectancy of a month from a preventive intervention  targeted at populations at average risk and a gain of a year  from a preventive intervention targeted at populations at elevated risk can both be considered large."<ref name="pmid9691106">{{cite journal |author=Wright JC, Weinstein MC |title=Gains in life expectancy from medical interventions--standardizing data on outcomes |journal=N Engl J Med |volume=339 |pages=380–6 |year=1998 |pmid=9691106 |doi=}}</ref>


===Medical informatics===
==Original research studies: levels of evidence==
[[Medical informatics]] is an essential adjunct to EBM, and focuses on creating tools to access and apply the best evidence for making decisions about patient care.<ref name="isbn0-443-07444-5"/>
'Levels of evidence' were first proposed in 1979 bye the Canadian Task Force on the Periodic Health Examination<ref name="pmid115569"/> then modified by the American College of Chest Physicians<ref name="pmid2914516">{{cite journal| author=Sackett DL| title=Rules of evidence and clinical recommendations on the use of antithrombotic agents. | journal=Chest | year= 1989 | volume= 95 | issue= 2 Suppl | pages= 2S-4S | pmid=2914516
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=2914516 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref><ref name="pmid3943408">{{cite journal |author=Sackett DL |title=Rules of evidence and clinical recommendations on the use of antithrombotic agents |journal=Chest |volume=89  |pages=2S–3S |year=1986 |pmid=3943408 |doi=}}</ref> to create a framework for judging the strength of research. An example of levels of evidence is, based on prior work<ref name="titleLevels of Evidence">{{cite web |url=http://www.eboncall.org/content/levels.html |title=Levels of Evidence |accessdate=2007-12-31 |author= |authorlink= |coauthors= |date= |format= |work= |publisher= |pages= |language= |archiveurl= |archivedate= |quote=}}</ref>:
* Level 1 - [[Randomized controlled trial]]s
* Level 2 - [[Cohort study|Cohort studies]]
* Level 3 - [[Case control study|Case control studies]]
* Level 4 - [[Case series]] and [[case report]]s. The important role of case reports have been described.<ref name="pmid18350575">{{cite journal |author=Sethi NK, Sethi PK |title=Evidence-based medicine vs medicine-based evidence |journal=Ann. Neurol. |volume= |issue= |pages= |year=2008 |pmid=18350575 |doi=10.1002/ana.21354 |url=http://dx.doi.org/10.1002/ana.21354}}</ref>  


Before practicing EBM, informaticians (or informationists) must be familiar with medical journals, literature databases, medical textbooks, practice guidelines, and the growing number of other dedicated evidence-based resources, like the Cochrane Database of Systematic Reviews and Clinical Evidence.<ref name="pmid15647224">{{cite journal |author=Mendelson D, Carino TV |title=Evidence-based medicine in the United States--de rigueur or dream deferred? |journal=Health Affairs (Project Hope) |volume=24 |pages=133–6 |year=2005 |pmid=15647224 |doi=10.1377/hlthaff.24.1.133 |issn=}}</ref>
These levels of evidence have been criticized as only representing one of two views of medical science.<ref>{{Cite journal | doi =  10.1371/journal.pmed.0050067 | volume = 5 | issue = 3 | pages = e67 EP - | last = Vandenbroucke | first = JP | title = Observational research, randomised trials, and two views of medical science | journal = PLoS Medicine | accessdate = 2008-03-11 | date = 2008-03-01 | url = http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0050067 }}</ref> Vandenbroucke proposes that the two views of medical research are:
# Evaluation of interventions. In this view, the [[randomized controlled trial]] is most important.
# Discovery and explanation. In this view, the [[randomized controlled trial]] is not supreme and observational studies, subgroup analyses, and secondary analyses are important.


Similarly, for practicing medical informatics properly, it is essential to have an understanding of EBM, including the ability to phrase an answerable question, locate and retrieve the best evidence, and critically appraise and apply it.<ref name="pmid11838463">{{cite journal |author=Hersh W |title=Medical informatics education: an alternative pathway for training informationists |journal=JMLA |volume=90 |pages=76–9 |year=2002 |pmid=11838463 |doi= |issn=}}</ref><ref name="pmid11838456">{{cite journal |author=Shearer BS ''et al.'' |title=Bringing the best of medical librarianship to the patient team |journal=JMLA |volume=90 |pages=22–31 |year=2002 |pmid=11838456 |doi= |issn=}}</ref>
In practice, [[randomized controlled trial]]s are available to support only 21%<ref name="pmid9701101">{{cite journal |author=Michaud G ''et al.'' |title=Are therapeutic decisions supported by evidence from health care research? |journal=Arch Intern Med |volume=158 |pages=1665–8 |year=1998 |pmid=9701101 |doi=}}</ref> to 53%<ref name="pmid7623571">{{cite journal |author=Ellis J ''et al.''|title=Inpatient general medicine is evidence based. A-Team, Nuffield Department of Clinical Medicine |journal=Lancet |volume=346  |pages=407–10 |year=1995 |pmid=7623571 |doi=}}</ref> of principal therapeutic decisions.<ref>{{cite web |url=http://www.shef.ac.uk/scharr/ir/percent.html |title=Percentage of practice that is evidence based? |accessdate=2007-11-15 |author=Booth A |authorlink= |coauthors= |date= |format= |work= |publisher= |pages= |language= |archiveurl= |archivedate= |quote=}}</ref> Due to this, evidence-based medicine has evolved to accept lesser levels of evidence when randomized controlled trials are not available.<ref name="pmid17213159">{{cite journal |author=Haynes RB |title=Of studies, syntheses, synopses, summaries, and systems: the "5S" evolution of information services for evidence-based healthcare decisions |journal=Evidence-based Medicine |volume=11 |pages=162–4 |year=2006 |pmid=17213159 |doi=10.1136/ebm.11.6.162-a}}</ref>


==Studies of the effectiveness of teaching evidence-based medicine==
The [http://www.gradeworkinggroup.org/ Grade Working Group] recognizes that assessing medical evidence involves attention to other dimensions than study design, and expanded upon the levels of evidence in 2004.<ref name="pmid15205295">{{cite journal |author=Atkins D ''et al'' |title=Grading quality of evidence and strength of recommendations |journal=BMJ |volume=328  |pages=1490 |year=2004 |pmid=15205295 |doi=10.1136/bmj.328.7454.1490 |url=http://bmj.com/cgi/pmidlookup?view=long&pmid=15205295}}</ref><ref name="pmid16388549">{{cite journal |author=Guyatt G, ''et al.'' |title=An emerging consensus on grading recommendations? |journal=ACP J Club |volume=144 |pages=A8–9 |year=2006 |pmid=16388549 |doi= |url=http://www.acpjc.org/Content/144/1/Issue/ACPJC-2006-144-1-A08.htm}}</ref> These dimensions include: study design; study quality; consistency of study results; and directness (e.g. how close does the research study mirror clinical practice)
A systematic review of the effectiveness of teaching EBM concluded "standalone teaching improved knowledge but not skills, attitudes or behaviour. Clinically integrated teaching improved knowledge, skills, attitudes and behaviour."<ref name="pmid15514348">{{cite journal |author=Coomarasamy A, Khan KS |title=What is the evidence that postgraduate teaching in evidence based medicine changes anything? A systematic review |journal=BMJ |volume=329 |pages=1017 |year=2004 |pmid=15514348 |doi=10.1136/bmj.329.7473.1017}}</ref> A second review concluded improvements in unvalidated measures of "knowledge, skills, attitudes or behavior."<ref name="pmid17655743">{{cite journal |author=Flores-Mateo G, Argimon JM |title=Evidence based practice in postgraduate healthcare education: a systematic review |journal=BMC Health Services Research |volume=7 |pages=119 |year=2007 |pmid=17655743 |doi=10.1186/1472-6963-7-119}}</ref> Neither review examined improvements in clinical care.


Two [[systematic review]]s of EBM provide the framework below for measuring outcomes.<ref name="pmid16954491">{{cite journal |author=Shaneyfelt T ''et al'' |title=Instruments for evaluating education in evidence-based practice: a systematic review |journal=JAMA |volume=296  |pages=1116–27 |year=2006 |pmid=16954491 |doi=10.1001/jama.296.9.1116|url=http://jama.ama-assn.org/cgi/content/full/296/9/1116}}</ref><ref name="pmid15514352">{{cite journal |author=Straus SE ''et al'' |title=Evaluating the teaching of evidence based medicine: conceptual framework |journal=BMJ |volume=329  |pages=1029–32 |year=2004 |pmid=15514352 |doi=10.1136/bmj.329.7473.1029}}</ref>
==Summarizing the evidence==
===Assessing a body of research evidence===
Several systems have been proposed to assess whether a body of research evidence establishes causality.


===Information retrieval===
{|align="right" cellpadding="10" style="background-color:#FFFFCC; width:50%; border: 1px solid #aaa; margin:20px; font-size: 92%;"
====Increasing use of information====
|'''Koch's postulates'''<ref name="pmid15372724">{{cite journal| author=Hopayian K| title=Why medicine still needs a scientific foundation: restating the hypotheticodeductive model - part two. | journal=Br J Gen Pract | year= 2004 | volume= 54 | issue= 502 | pages= 402-3; discussion 404-5 | pmid=15372724
A [[randomized controlled trial]] of volunteer senior medical students found that access to information portal on a handheld computer increased self-reported use of information.<ref name="pmid14604933">{{cite journal |author=Leung GM ''et al.'' |title=Randomised controlled trial of clinical decision support tools to improve learning of evidence based medicine in medical students |journal=BMJ |volume=327 |pages=1090 |year=2003 |pmid=14604933 |doi=10.1136/bmj.327.7423.1090}}</ref> The information portal contained multiple pre-appraised resources, including a textbook and drug resource, and would best resemble the "user" mode. The study was not able to isolate which resources in the portal had increased use. It is possible that the benefit was solely due to the textbook or drug resource.
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=15372724 | pmc=PMC1266186 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref>
* "The bacterium must be present in every case of the disease."
* "The bacterium must be isolated from the diseased host and grown in pure culture."
* "The specific disease must be reproduced when a pure culture of the bacterium is inoculated into a healthy susceptible host."
* "The bacterium must be recoverable from the experimentally infected host."
|}
In the 1880's Koch proposed postulates ([[Koch's Postulates]]) that suggest association.<ref name="pmid16339091">{{cite journal |author=Kaufmann SH |title=Robert Koch, the Nobel Prize, and the ongoing threat of tuberculosis |journal=N. Engl. J. Med. |volume=353 |issue=23 |pages=2423–6 |year=2005 |month=December |pmid=16339091 |doi=10.1056/NEJMp058131 |url=http://content.nejm.org/cgi/pmidlookup?view=short&pmid=16339091&promo=ONFLNS19 |issn=}}</ref> However, even though the postulates focus on establishing casuality among infections diseases, examples have emerged that violate his postulates.<ref name="pmid15372724">{{cite journal| author=Hopayian K| title=Why medicine still needs a scientific foundation: restating the hypotheticodeductive model - part two. | journal=Br J Gen Pract | year= 2004 | volume= 54 | issue= 502 | pages= 402-3; discussion 404-5 | pmid=15372724
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=15372724 | pmc=PMC1266186 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref>


A randomized controlled trial of teaching and encouraging use of [[MEDLINE]] by medical resident physicians showed increased searching for evidence during 6-8 weeks of observation.<ref name="pmid11903763">{{cite journal |author=Cabell CH ''et al.''|title=Resident utilization of information technology |journal=J Gen Intern Med |volume=16 |pages=838–44 |year=2001 |pmid=11903763 |doi=}}</ref> Based on the median number of searches and hours spent searching, each search averaged 22 minutes, which may not be sustainable over the long term.
{|align="right" cellpadding="10" style="background-color:#FFFFCC; width:50%; border: 1px solid #aaa; margin:20px; font-size: 92%;"
|'''Bradford Hill criteria'''<ref name="pmid14283879">{{cite journal |author=Hill AB |title=The Environment And Disease: Association Or Causation? |journal=Proc. R. Soc. Med. |volume=58 |pages=295–300 |year=1965 |month=May |pmid=14283879 |pmc=1898525 |doi= |url= |issn=}}</ref>
* Strength or magnitude of association?
* Consistency of association across studies?
* Specificity of association?
* Temporality of association?
* Plausibility based on biological knowledge?
* Biological gradient: or dose-response relationship?
* Coherence? Does the proposed association explain other observations?
* Experimental evidence?
* Analogy?
|}


====Improving clinical care====
The [[Bradford Hill]] criteria were proposed in 1965 in response to studies of the association between [[tobacco]] and [[lung cancer]]:<ref name="pmid14283879">{{cite journal |author=Hill AB |title=The Environment And Disease: Association Or Causation? |journal=Proc. R. Soc. Med. |volume=58 |pages=295–300 |year=1965 |month=May |pmid=14283879 |pmc=1898525 |doi= |url= |issn=}}</ref>
Teaching "''user''" mode only using syntheses and synopses, without summaries, has not shown benefit in two studies. A controlled trial of teaching the "user" mode (see above) was negative.<ref name="pmid17683300">{{cite journal |author=Shuval K ''et al.'' |title=Evaluating the impact of an evidence-based medicine educational intervention on primary care doctors' attitudes, knowledge and clinical behaviour: a controlled trial and before and after study |journal=Journal of Evaluation in Clinical Practice |volume=13 |pages=581–98 |year=2007 |pmid=17683300 |doi=10.1111/j.1365-2753.2007.00859.x}}</ref> However, this study encouraged the use of syntheses and synopses and did not encourage the more practical "summaries" (evidence-based textbooks) of the "5S" search strategy.<ref name="pmid17080967">{{cite journal |author=Haynes RB |title=Of studies, syntheses, synopses, summaries, and systems: the "5S" evolution of information services for evidence-based health care decisions |journal=ACP J Club |volume=145 |pages=A8 |year=2006 |pmid=17080967 |doi=}}</ref> A quasi-randomized, controlled investigation of teaching medical students the use of studies, syntheses, and synopses using an automated search engine was negative.<ref name="pmid11532204">{{cite journal |author=Badgett RG ''et al.''|title=Teaching clinical informatics to third-year medical students: negative results from two controlled trials |journal=BMC Medical Education |volume=1 |pages=3 |year=2001 |pmid=11532204 |doi=}}[http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=11532204 PubMed Central]</ref>


===Information awareness===
More explicit methods have been proposed by groups such as the [[U.S. Preventive Services Task Force]] (USPSTF) (see yellow text box above), the American College of Chest Physicians<ref name="pmid2914516"/><ref name="pmid3943408"/> and the Grade Working Group<ref name="titleGRADE working group">{{cite web |url=http://www.gradeworkinggroup.org/ |title=GRADE working group |accessdate=2007-11-23 |format= |work=}}</ref> The Grade Working Group combines the quality of research studies with their clinical relevance.<ref name="pmid15205295"/> For example, this allows comparing a randomized control trial in a population that is not exactly like the population of interest versus a cohort study that is from a relevant population. The concept that there are multiple dimensions in assessing evidence has been expanded to a proposal that assessing evidence is not a linear process, but is circular.<ref name="pmid16796762">{{cite journal |author=Walach H ''et al.'' |title=Circular instead of hierarchical: methodological principles for the evaluation of complex interventions |journal=BMC Med Res Methodol |volume=6 |pages=29 |year=2006 |pmid=16796762 |doi=10.1186/1471-2288-6-29}}</ref>
====Increasing use of information====
A cluster randomized trial of McMaster Premium LiteratUre Service (PLUS) led to " increased the utilization of evidence-based information from a digital library by practicing physicians."<ref name="pmid16929034">{{cite journal |author=Haynes RB ''et al.'' |title=McMaster PLUS: a cluster randomized clinical trial of an intervention to accelerate clinical use of evidence-based information from digital libraries |journal=Journal of the American Medical Informatics Association : JAMIA |volume=13  |pages=593–600 |year=2006 |pmid=16929034 |doi=10.1197/jamia.M2158}}</ref>


====Improving clinical care====
Diamond has proposed a method using Bayesian beliefs for assessing medical evidence that categorizes beliefs similarly to how evidence is assessed in the legal system.<ref name="pmid19667308">{{cite journal| author=Diamond GA, Kaul S| title=Bayesian classification of clinical practice guidelines. | journal=Arch Intern Med | year= 2009 | volume= 169 | issue= 15 | pages= 1431-5 | pmid=19667308
No controlled studies have addressed improving clinical care by use of information awareness strategies.
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=clinical.uthscsa.edu/cite&email=badgett@uthscdsa.edu&retmode=ref&cmd=prlinks&id=19667308 | doi=10.1001/archinternmed.2009.235 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref>


===Clinical reasoning===
=====The legal system=====
====Improving clinical care====
:See [[Medical malpractice#Standard of care]]
A controlled trial of teaching Bayesian principles (probabilistic reasoning) "improves the efficiency of test ordering."<ref name="pmid2492066">{{cite journal |author=Davidoff F ''et al.'' |title=Changing test ordering behavior. A randomized controlled trial comparing probabilistic reasoning with cost-containment education |journal=Medical care |volume=27  |pages=45–58 |year=1989 |pmid=2492066 |doi=}}</ref>


==Studies on how to teach evidence-based medicine==
===Systematic review===
This sections includes implications based on the preceding discussion on studies of effectiveness. In addition, this section includes other studies or reports of teaching methods, even though these methods have not been subjected to study of effect on clinical outcomes.
{{main|Systematic review}}
A systematic review is a summary of healthcare research that involves a thorough literature search and critical appraisal of individual studies to identify the valid and applicable evidence. It often, but not always, uses appropriate techniques ([[meta-analysis]]) to combine studies, and may grade the quality of the particular pieces of evidence according to the methodology used, and according to strengths or weaknesses of the study design. While many systematic reviews are based on an explicit [[quantitative research|quantitative]] [[meta-analysis]] of available data, there are also [[qualitative research|qualitative]] reviews which nonetheless adhere to the standards for gathering, analyzing and reporting evidence.


===Ask===
===Clinical practice guidelines===
===Acquire===
{{main|Clinical practice guideline}}
A search strategy similar to the 5S strategy should be taught for use when the searcher has limited time available during clinical care. This is based on one positive study of its use<ref name="pmid17082828">{{cite journal |author=Patel MR ''et al.'' |title=Randomized trial for answers to clinical questions: evaluating a pre-appraised versus a [[MEDLINE]] search protocol |journal=JMLA |volume=94 |pages=382–7 |year=2006 |pmid=17082828 |doi=}}</ref> and two negative studies<ref name="pmid17683300"/><ref name="pmid11532204"/> of teaching the use using secondary and primary publications. In addition, indirect evidence on the time needed to search also supports the emphasis on using tertiary publications. Doctors may have two minutes available to search<ref name="pmid10435959">{{cite journal |author=Ely JW ''et al.'' |title=Analysis of questions asked by family doctors regarding patient care |journal=BMJ |volume=319 |pages=358–61 |year=1999 |pmid=10435959 |doi=}}</ref>, whereas using MEDLINE may take 20 minutes or more.<ref name="pmid8708623">{{cite journal |author=Chambliss ML, Conley J |title=Answering clinical questions |journal=The Journal of Family Practice |volume=43  |pages=140–4 |year=1996 |pmid=8708623 |doi=}}</ref><ref name="pmid11903763">{{cite journal |author=Cabell CH ''et al.'' |title=Resident utilization of information technology |journal=J Gen Intern Med |volume=16|pages=838–44 |year=2001 |pmid=11903763 |doi=}}</ref>
Clinical practice guidelines are defined as "Directions or principles presenting current or future rules of policy for assisting health care practitioners in patient care decisions regarding diagnosis, therapy, or related clinical circumstances. The guidelines may be developed by government agencies at any level, institutions, professional societies, governing boards, or by the convening of expert panels. The guidelines form a basis for the evaluation of all aspects of health care and delivery."<ref>{{cite web |url=http://www.nlm.nih.gov/cgi/mesh/2007/MB_cgi?mode=&term=practice+guidelines |title=Clinical practice guidelines|author=National Library of Medicine |accessdate=2007-10-19 |format= |work=}}</ref>


Teaching [[MEDLINE]] searching would be appropriate for ''Doers'' who might be willing to invest time in searching MEDLINE when not hurried by clinical care. Based on studies of common errors in searching MEDLINE, learners should be taught Medical Subject Headings (MeSH) terms and their explosion, appropriate limits, and best evidence to search for.<ref name="pmid16186614">{{cite journal |author=Gruppen LD ''et al.''|title=A controlled comparison study of the efficacy of training medical students in evidence-based medicine literature searching skills |journal=Academic medicine |volume=80  |pages=940–4 |year=2005 |pmid=16186614 |doi=}}</ref> The mnemonic PEARL may guide how to each.<ref name="pmid16501264">{{cite journal |author=Silk H ''et al.''|title=A new way to integrate clinically relevant technology into small-group teaching |journal=Academic Medicine  |volume=81 |pages=239–44 |year=2006 |pmid=16501264 |doi=}}</ref> PEARL stands for:
==Incorporating evidence into clinical care==
# "Choose a ''''P'''replanned search intervention'"
''see also [[Teaching evidence-based medicine]]''
# "Allow learners to ''''E'''xecute the search,' thus committing themselves"
===Medical informatics===
# "''''A'''llow learners to teach other learners' about their search process
{{main|Medical informatics}}
# "''''R'''eview the quality of evidence' for the information found"
Practicing clinicians cite the lack of time for keeping up with emerging medical evidence that may change clinical practice.<ref name="pmid15647224">{{cite journal |author=Mendelson D, Carino TV |title=Evidence-based medicine in the United States--de rigueur or dream deferred? |journal=Health Affairs (Project Hope) |volume=24 |pages=133–6 |year=2005 |pmid=15647224 |doi=10.1377/hlthaff.24.1.133 |issn=}}</ref> [[Medical informatics]] is an essential adjunct to EBM, and focuses on creating tools to access and apply the best evidence for making decisions about patient care.<ref name="isbn0-443-07444-5"/> Before practicing EBM, informaticians (or informationists) must be familiar with medical [[academic journal|journals]], literature databases, medical textbooks, practice guidelines, and the growing number of other evidence-based resources, like the Cochrane Database of Systematic Reviews and Clinical Evidence.<ref name="pmid15647224">{{cite journal |author=Mendelson D, Carino TV |title=Evidence-based medicine in the United States--de rigueur or dream deferred? |journal=Health Affairs (Project Hope) |volume=24 |pages=133–6 |year=2005 |pmid=15647224 |doi=10.1377/hlthaff.24.1.133 |issn=}}</ref> Similarly, for practicing medical informatics properly, it is essential to have an understanding of EBM, including the ability to phrase an answerable question, locate and retrieve the best evidence, and critically appraise and apply it.<ref name="pmid11838463">{{cite journal |author=Hersh W |title=Medical informatics education: an alternative pathway for training informationists |journal=JMLA |volume=90 |pages=76–9 |year=2002 |pmid=11838463 |doi= |issn=}}</ref><ref name="pmid11838456">{{cite journal |author=Shearer BS ''et al.'' |title=Bringing the best of medical librarianship to the patient team |journal=JMLA |volume=90 |pages=22–31 |year=2002 |pmid=11838456 |doi= |issn=}}</ref>
# "Discuss ''''L'''essons of the search.'"
 
===Appraise===
===Apply===
====Clinical reasoning====
There are various methods of clinical reasoning include probabilistic (Bayesian), causal (physiologic), and deterministic (rule-based).<ref name="pmid2655522">{{cite journal | author = Kassirer JP | title = Diagnostic reasoning | journal = Ann Intern Med | volume = 110 | pages = 893–900 | year = 1989 | pmid = 2655522 | doi = }}</ref> In addition, medical experts rely more on pattern recognition which is faster and less prone to error<ref name="pmid7503827">{{cite journal | author = Leape LL | title = Error in medicine | journal = JAMA | volume = 272 | pages = 1851–7 | year = 1994 | pmid = 7503827 | doi = }}</ref>; however, clinical experts seem flexible and may use whichever method of reasoning most easily represents and solves a given problem.<ref name="pmid17124025">{{cite journal | author = Norman G | title = Building on experience--the development of clinical reasoning | journal = N Engl J Med | volume = 355  | pages = 2251–2 | year = 2006 | pmid = 17124025 | doi = 10.1056/NEJMe068134}}</ref> Scales to measure clinical reasoning have been proposed.<ref name="pmid9231115">{{cite journal | author = Boshuizen HP ''et al.''| title = Measuring knowledge and clinical reasoning skills in a problem-based curriculum | journal = Medical education | volume = 31 | pages = 115–21 | year = 1997 | pmid = 9231115 | doi = }}</ref> Explicit Bayesian thinking with precise numbers is rarely done.<ref name="pmid3277516">{{cite journal | author = Moskowitz AJ ''et al.''| title = Dealing with uncertainty, risks, and tradeoffs in clinical decisions. A cognitive science approach | journal = Ann. Intern. Med. | volume = 108| pages = 435–49 | year = 1988 | pmid = 3277516 | doi = }}</ref><ref name="pmid9576412">{{cite journal |author=Reid MC, Lane DA, Feinstein AR |title=Academic calculations versus clinical judgments: practicing physicians' use of quantitative measures of test accuracy |journal=Am J Med |volume=104 |pages=374–80 |year=1998 |pmid=9576412 |doi=}}</ref> Basic science knowledge is probably "encapsulated" into clinical knowledge.<ref name="pmid16043534">{{cite journal | author = de Bruin AB ''et al.'' | title = The role of basic science knowledge and clinical knowledge in diagnostic reasoning: a structural equation modeling approach | journal = Academic Medicine  | volume = 80 | pages = 765–73 | year = 2005 | pmid = 16043534 | doi = }}</ref>


{| align="right" border="1"
===Health care quality assurance===
|+'''Competing-hypotheses heuristic'''<ref name="pmid3385753">{{cite journal | author = Wolf FM ''et al.'' | title = Use of the competing-hypotheses heuristic to reduce 'pseudodiagnosticity' | journal = J Med Educ | volume = 63 | pages = 548–54 | year = 1988 | pmid = 3385753 | doi = }}</ref>
{{main|Health care quality assurance}}
! Finding || Disease A || Disease B
==Criticisms of EBM==
|-
[[Image:Hume.jpg|thumb|right|Statue of [[David Hume]]. ''"Man is a reasonable being; and as such, receives from science his proper food and nourishment: But so narrow are the bounds of human understanding, that little satisfaction can be hoped for in this particular..."''
| Fever || 66%  || cell B
[[David Hume|Hume]] recognised clearly the difficulties in gaining a general understanding merely by accumulating observations.]]
|-
| Rash || cell C  || cell D
|-
| Colspan="3" | The most important missing information is cell B
|}
Possible strategies to improve clinical reasoning have been reviewed<ref name="pmid17124019">{{cite journal |author=Bowen JL |title=Educational strategies to promote clinical diagnostic reasoning |journal=N Engl J Med |volume=355  |pages=2217–25 |year=2006 |pmid=17124019 |doi=10.1056/NEJMra054782}}</ref><ref name="pmid12377672">{{cite journal |author=Graber M ''et al.'' |title=Reducing diagnostic errors in medicine: what's the goal? |journal=Academic Medicine |volume=77  |pages=981–92 |year=2002 |pmid=12377672 |doi=}}</ref> and using problem-based learning<ref name="pmid12377672"/>, include teaching appropriate problem representation creating a one-sentence summary of a case<ref name="pmid17124019"/>, standardized patients<ref name="pmid16423099">{{cite journal |author=Windish DM ''et al.'' |title=Teaching medical students the important connection between communication and clinical reasoning |journal=J Gen Intern Med |volume=20 |pages=1108–13 |year=2005 |pmid=16423099 |doi=10.1111/j.1525-1497.2005.0244.x}}</ref>, teaching hypothetico-deductive reasoning<ref name="pmid11893348">{{cite journal |author=Wiese J ''et al.''|title=Improving oral presentation skills with a clinical reasoning curriculum: a prospective controlled study |journal=Am J Med |volume=112 |pages=212–8 |year=2002 |pmid=11893348 |doi=}}</ref><ref name="pmid7070446">{{cite journal |author=Eddy DM, Clanton CH |title=The art of diagnosis: solving the clinicopathological exercise |journal=N Engl J Med |volume=306 |pages=1263–8 |year=1982 |pmid=7070446 |doi=}}</ref>, cognitive forcing strategies<ref name="pmid11073470">{{cite journal |author=Croskerry P |title=The cognitive imperative: thinking about how we think |journal=Academic Emergency Medicine |volume=7 |pages=1223–31 |year=2000 |pmid=11073470 |doi=}}</ref><ref name="pmid12414468">{{cite journal |author=Croskerry P |title=Achieving quality in clinical decision making: cognitive strategies and detection of bias |journal=Academic Emergency Medicine |volume=9 |pages=1184–204 |year=2002 |pmid=12414468 |doi=}}</ref> to avoid premature closure<ref name="pmid3736379">{{cite journal |author=Dubeau CE ''et al.''|title=Premature conclusions in the diagnosis of iron-deficiency anemia: cause and effect |journal=Medical Decision Making  |volume=6  |pages=169–73 |year=1986 |pmid=3736379 |doi=}}</ref>, teaching the competing-hypotheses heuristic<ref name="pmid3385753">{{cite journal | author = Wolf FM ''et al.'' | title = Use of the competing-hypotheses heuristic to reduce 'pseudodiagnosticity' | journal = J Med Educ | volume = 63 | pages = 548–54 | year = 1988 | pmid = 3385753 | doi = }}</ref>, and using fuzzy-trace theory<ref name="pmid11251760">{{cite journal |author=Lloyd FJ, Reyna VF |title=A web exercise in evidence-based medicine using cognitive theory |journal=J Gen Intern Med|volume=16 |pages=94–9 |year=2001 |pmid=11251760 |doi=}} [http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=11251760 PubMed Central]</ref>.


Studies are inconclusive on using cognitive feedback<ref name="pmid7898300">{{cite journal |author=Poses RM ''et al.''|title=You can lead a horse to water--improving physicians' knowledge of probabilities may not affect their decisions |journal=Medical Decision Making |volume=15  |pages=65–75 |year=1995 |pmid=7898300 |doi=}}</ref> and teaching logic<ref name="pmid3742999">{{cite journal |author=Cheng PW ''et al.'' |title=Pragmatic versus syntactic approaches to training deductive reasoning |journal=Cognitive Psychology |volume=18 |pages=293–328 |year=1986 |pmid=3742999 |doi=10.1016/0010-0285(86)90002-2}}</ref><ref name="pmid16907682">{{cite journal | author = Jenicek M | title = The hard art of soft science: Evidence-Based Medicine, Reasoned Medicine or both? | journal = Journal of Evaluation in Clinical Practice | volume = 12 | pages = 410–9 | year = 2006 | pmid = 16907682 | doi = 10.1111/j.1365-2753.2006.00718.x}}</ref>.
There are a number of criticisms of EBM.<ref name="pmid17264255">{{cite journal |author=Straus S ''et al.'' |title=Misunderstandings, misperceptions, and mistakes |journal=Evidence-based medicine |volume=12 |pages=2–3 |year=2007 |pmid=17264255 |doi=10.1136/ebm.12.1.2-a}}</ref><ref name="pmid11033714">{{cite journal |author=Straus SE, McAlister FA |title=Evidence-based medicine: a commentary on common criticisms |journal=CMAJ |volume=163 |pages=837–41 |year=2000 |pmid=11033714 |doi=}}</ref>


===Assess===
===Excessive reliance on empiricism and deduction===
EBM has been criticized as an attempt to define knowledge in medicine in the same way that was done unsuccessfully by the logical positivists in epistemology, "trying to establish a secure foundation for scientific knowledge based only on observed facts" <ref name="pmid12204023">{{cite journal |author=Goodman SN |title=The mammography dilemma: a crisis for evidence-based medicine? |journal=Ann Intern Med |volume=137  |pages=363–5 |year=2002 |pmid=12204023 |doi=|url=http://www.annals.org/cgi/content/full/137/5_Part_1/363}}</ref>and not recognizing the fallible nature of knowledge in general.<ref name="pmid10970003">{{cite journal |author=Upshur RE |title=Seven characteristics of medical evidence |journal=J Eval Clin Pract |volume=6  |pages=93–7 |year=2000 |pmid=10970003 |doi= |issn=}}</ref> The problem of relying on empiric evidence as a foundation for knowledge was recognized over 100 years ago and is known as the "Problem of Induction" or "[[David Hume|Hume]]'s Problem".<ref>{{cite web |url=http://plato.stanford.edu/entries/induction-problem/ |title=The Problem of Induction (Stanford Encyclopedia of Philosophy) |accessdate=2007-11-16 |author=Vickers, J |authorlink= |coauthors= |date=2006 |format= |work= |publisher=Stanford Encyclopedia of Philosophy |pages= |language= |archiveurl= |archivedate= |quote=}}</ref> Alternative [[logic]] is induction and abduction.<ref name="pmid16373725">{{cite journal| author=Rapezzi C, Ferrari R, Branzi A| title=White coats and fingerprints: diagnostic reasoning in medicine and investigative methods of fictional detectives. | journal=BMJ | year= 2005 | volume= 331 | issue= 7531 | pages= 1491-4 | pmid=16373725
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=16373725 | doi=10.1136/bmj.331.7531.1491 | pmc=PMC1322237 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref>


==Criticisms of evidence-based medicine==
===Inability to individualize for each patient===
There are a number of criticisms of evidence-based medicine.<ref name="pmid17264255">{{cite journal |author=Straus S, Haynes B, Glasziou P, Dickersin K, Guyatt G |title=Misunderstandings, misperceptions, and mistakes |journal=Evidence-based medicine |volume=12 |issue=1 |pages=2–3 |year=2007 |pmid=17264255 |doi=10.1136/ebm.12.1.2-a}}</ref><ref name="pmid11033714">{{cite journal |author=Straus SE, McAlister FA |title=Evidence-based medicine: a commentary on common criticisms |journal=CMAJ : Canadian Medical Association journal &#61; journal de l'Association medicale canadienne |volume=163 |issue=7 |pages=837–41 |year=2000 |pmid=11033714 |doi=}}</ref>
A general problem with EBM is that it seeks to make recommendations for treatment that (on balance) are likely to provide the best treatment for most patients. However what is the best treatment for most patients is not necessarily the best treatment for a particular individual patient. The causes of disease, and the patient responses to treatment all vary considerably, and are affected for example by the individual's genetic make-up, their particular history, and by factors of individual lifestyle. To take these properly into account requires the clinical experience of the treating physician, and over-reliance upon recommendations based upon statistical outcomes of treatments given in a standardised way to large populations may not always lead to the best care for a particular individual.
 
===Lack of randomized controlled trials for clinical decisions===
[[Randomized controlled trial]]s are available to support to 21%<ref name="pmid9701101">{{cite journal |author=Michaud G, McGowan JL, van der Jagt R, Wells G, Tugwell P |title=Are therapeutic decisions supported by evidence from health care research? |journal=Arch. Intern. Med. |volume=158 |issue=15 |pages=1665–8 |year=1998 |pmid=9701101 |doi=}}</ref> 53%<ref name="pmid7623571">{{cite journal |author=Ellis J, Mulligan I, Rowe J, Sackett DL |title=Inpatient general medicine is evidence based. A-Team, Nuffield Department of Clinical Medicine |journal=Lancet |volume=346 |issue=8972 |pages=407–10 |year=1995 |pmid=7623571 |doi=}}</ref> of principle therapeutic decisions.<ref>{{cite web |url=http://www.shef.ac.uk/scharr/ir/percent.html |title=Percentage of practice that is evidence based? |accessdate=2007-11-15 |author=Booth, A |authorlink= |coauthors= |date= |format= |work= |publisher= |pages= |language= |archiveurl= |archivedate= |quote=}}</ref> Due to this, evidence-based medicine has evolved to accept lesser levels of evidence when randomized controlled trials are not available.<ref name="pmid17213159">{{cite journal |author=Haynes RB |title=Of studies, syntheses, synopses, summaries, and systems: the "5S" evolution of information services for evidence-based healthcare decisions |journal=Evidence-based medicine |volume=11 |issue=6 |pages=162–4 |year=2006 |pmid=17213159 |doi=10.1136/ebm.11.6.162-a}}</ref>


===Ulterior motives===
===Ulterior motives===
An early criticism of evidence-based medicine is that it will be a guise for rationing resources or other goals that are not in the interest of the patient.<ref name="pmid7742683">{{cite journal |author=Grahame-Smith D |title=Evidence based medicine: Socratic dissent |journal=BMJ |volume=310 |issue=6987 |pages=1126–7 |year=1995 |pmid=7742683 |doi=|url=http://www.bmj.com/cgi/content/full/310/6987/1126}}</ref><ref name="pmid11525707">{{cite journal |author=Formoso G, Liberati A, Magrini N |title=Practice guidelines: useful and "participative" method? Survey of Italian physicians by professional setting |journal=Arch. Intern. Med. |volume=161 |issue=16 |pages=2037–42 |year=2001 |pmid=11525707 |doi=}}</ref> In 1994, the [[American Medical Association]] helped introduce the "Patient Protection Act" in Congress to reduce the power of insurers to use guidelines to deny payment for a medical services.<ref>{{cite web |url=http://query.nytimes.com/gst/fullpage.html?res=9B0DE1DC1E38F937A15756C0A962958260&sec=&spon=&partner=permalink&exprod=permalink |title=A.M.A. and Insurers Clash Over Restrictions on Doctors - New York Times |author=Pear, R|accessdate=2007-11-14 |format= |work=}}</ref>
An early criticism of EBM is that it will be a guise for rationing resources or other goals that are not in the interest of the patient.<ref name="pmid7742683">{{cite journal |author=Grahame-Smith D |title=Evidence based medicine: Socratic dissent |journal=BMJ |volume=310 |pages=1126–7 |year=1995 |pmid=7742683 |doi=|url=http://www.bmj.com/cgi/content/full/310/6987/1126}}</ref><ref name="pmid11525707">{{cite journal |author=Formoso G ''et al.'' |title=Practice guidelines: useful and "participative" method? Survey of Italian physicians by professional setting |journal=Arch Intern Med |volume=161 |pages=2037–42 |year=2001 |pmid=11525707 |doi=}}</ref> In 1994, the [[American Medical Association]] helped introduce the "Patient Protection Act" in Congress to reduce the power of insurers to use guidelines to deny payment for a medical services.<ref>{{cite web |url=http://query.nytimes.com/gst/fullpage.html?res=9B0DE1DC1E38F937A15756C0A962958260&sec=&spon=&partner=permalink&exprod=permalink |title=A.M.A. and Insurers Clash Over Restrictions on Doctors - New York Times |author=Pear, R|accessdate=2007-11-14 |format= |work=}}</ref> As a possible example, Milliman Care Guidelines state they produce "evidence-based clinical guidelines since 1990".<ref>{{cite web |url=http://www.careguidelines.com/company/ |title=Evidence-Based Clinical Guidelines by Milliman Care Guidelines |accessdate=2007-11-14 |format= |work=}}</ref> In 2000, an academic pediatrician sued Milliman for using his name as an author on a practice guidelines that he stated were "dangerous" <ref>{{cite web |url=http://www.chron.com/CDA/archives/archive.mpl?id=2000_3199375 |title=Cost-cutting guide used by HMOs called `dangerous' / Doctor on UT-Houston Medical School staff sues publisher |author=Nissimov, R|publisher=Houston Chronicle|year=2000|accessdate=2007-11-14 |format= |work=}}</ref><ref>{{cite web |url=http://www.chron.com/CDA/archives/archive.mpl?id=2000_3254627 |title=Judge tells firm to explain how pediatric rules derived |author=Nissimov, R|year=2000|accessdate=2007-11-14 |format= |work=|publisher= Houston Chronicle}}</ref><ref>{{cite web |url=http://www.wsj.com |title=Insurance Health-Care Guidelines Are Assailed for Putting Patients Last |author=Martinez, B|year=2000|publisher=Wall Street Journal|format= |work=}}</ref> A similar suit disputing the origin of care decisions at Kaiser has been filed.<ref>{{cite web |url=http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2002/01/07/BU178030.DTL&type=business |title=Lawsuit disputes truth of Kaiser Permanente ads |accessdate=2007-11-14 |author=Colliver, V |authorlink= |coauthors= |date=1/07/2002|year=2002 |format= |work= |publisher=San Francisco Chronicle |pages= |language= |archiveurl= |archivedate= |quote=}}</ref> The outcomes of both suits are not known.


As a possible example, Milliman Care Guidelines state they produce "evidence-based clinical guidelines since 1990".<ref>{{cite web |url=http://www.careguidelines.com/company/ |title=Evidence-Based Clinical Guidelines by Milliman Care Guidelines |accessdate=2007-11-14 |format= |work=}}</ref> In 2000, an academic pediatrician sued Milliman for using his name as an author on a practice guidelines that he stated were "dangerous" <ref>{{cite web |url=http://www.chron.com/CDA/archives/archive.mpl?id=2000_3199375 |title=Cost-cutting guide used by HMOs called `dangerous' / Doctor on UT-Houston Medical School staff sues publisher |author=Nissimov, R|publisher=Houston Chronicle|year=2000|accessdate=2007-11-14 |format= |work=}}</ref><ref>{{cite web |url=http://www.chron.com/CDA/archives/archive.mpl?id=2000_3254627 |title=Judge tells firm to explain how pediatric rules derived |author=Nissimov, R|year=2000|accessdate=2007-11-14 |format= |work=|publisher= Houston Chronicle}}</ref><ref>{{cite web |url=http://www.wsj.com |title=Insurance Health-Care Guidelines Are Assailed for Putting Patients Last |author=Martinez, B|year=2000|publisher=Wall Street Journal|format= |work=}}</ref> A similar suit disputing the origin of care decisions at Kaiser has been filed.<ref>{{cite web |url=http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2002/01/07/BU178030.DTL&type=business |title=Lawsuit disputes truth of Kaiser Permanente ads |accessdate=2007-11-14 |author=Colliver, V |authorlink= |coauthors= |date=1/07/2002|year=2002 |format= |work= |publisher=San Francisco Chronicle |pages= |language= |archiveurl= |archivedate= |quote=}}</ref> The outcomes of both suits are not known.
Conversely, [[clinical practice guideline]]s by the [[Infectious Disease Society of America]] are being investigated by Connecticut's attorney general on grounds that the guidelines, which do not recognize a chronic form of Lyme disease, are anticompetitive.<ref>{{cite web |url=http://www.the-scientist.com/news/print/49605/ |title=The Scientist : State official subpoenas infectious disease group|author=Warner, S |accessdate=2007-11-14|date=2/7/2007|year=2007 |format= |work=}}</ref><ref>{{cite web |url=http://www.acponline.org/journals/news/jan-feb07/lyme.htm |title=ACP Observer, January-February 2007 - Experts spar over treatment for 'chronic' Lyme disease|author=Gesensway, D|year=2007 |accessdate=2007-11-14 |format= |work=}}</ref>


Conversely, [[clinical practice guideline]]s by the [[Infectious Disease Society of America]] are being investigated by Connecticut's attorney general on grounds that the guidelines, which do not recognize a chronic form of Lyme disease, are anticompetitive.<ref>{{cite web |url=http://www.the-scientist.com/news/print/49605/ |title=The Scientist : State official subpoenas infectious disease group|author=Warner, S |accessdate=2007-11-14|date=2/7/2007|year=2007 |format= |work=}}</ref><ref>{{cite web |url=http://www.acponline.org/journals/news/jan-feb07/lyme.htm |title=ACP Observer, January-February 2007 - Experts spar over treatment for 'chronic' Lyme disease|author=Gesensway, D|year=2007 |accessdate=2007-11-14 |format= |work=}}</ref>
===EBM not recognizing the limits of clinical epidemiology===
EBM is a set of techniques derived from clinical epidemiology, but a common criticism is that epidemiology can show ''association'' but not ''causation''.  While clinical epidemiology has its role in inspiring clinical decisions if it is complemented with testable hypotheses on disease,<ref name="pmid-10970004">{{cite journal |author=Djulbegovic B ''et al.''|title=Evidentiary challenges to evidence-based medicine |journal=Journal of evaluation in clinical practice |volume=6 |pages=99–109 |year=2000 |pmid=10970004 |doi= |issn=}}</ref> many critics consider that EBM is a form of clinical epidemiology which became so common in health care systems, and imposed such an empiricist bias on medical research, that it has undermined the notion of causal inference in clinical practice.<ref>Charlton BG. [Book Review: Evidence-based medicine: how to practice and teach EBM by Sackett DL, Richardson WS, Rosenberg W, Haynes RB. http://www.hedweb.com/bgcharlton/journalism/ebm.html] Journal of Evaluation in Clinical Practice. 1997; 3:169-172</ref> It is argued that it has even become condemnable to use common sense,<ref name="pmid15189382">{{cite journal |author=Michelson J |title=Critique of (im)pure reason: evidence-based medicine and common sense |journal=J Evaluation Clin Pract|volume=10 |pages=157–61 |year=2004 |pmid=15189382 |doi=10.1111/j.1365-2753.2003.00478.x}}</ref> as was cleverly illustrated in a systematic review of randomized controlled trials studying the effects of parachutes against gravitational challenges (free falls).<ref name="pmid14684649">{{cite journal |author=Smith GC, Pell JP |title=Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials |journal=BMJ |volume=327  |pages=1459–61 |year=2003 |pmid=14684649 |doi=10.1136/bmj.327.7429.1459 |issn=}}</ref>


===Epistemology===
[[Image:Lorenz butterfly.jpg|160px|right|thumb|Lorenz butterfly showing two attractors in a complex, chaotic system. See [[complexity science]].]]
Evidence-based medicine has been criticized as an attempt to define knowledge in medicine in the same way that was done unsuccessfully by the logical positivists in epistemology, "trying to establish a secure foundation for scientific knowledge based only on observed facts".<ref name="pmid12204023">{{cite journal |author=Goodman SN |title=The mammography dilemma: a crisis for evidence-based medicine? |journal=Ann Intern Med |volume=137  |pages=363–5 |year=2002 |pmid=12204023 |doi=|url=http://www.annals.org/cgi/content/full/137/5_Part_1/363}}</ref>
===Complexity science===
{{main|complexity science}}
[[Complexity science]] and chaos theory are proposed as further explaining the nature of medical knowledge<ref name="isbn1-85775-724-6">{{cite book |author=Sweeney, Kieran  |title=Complexity in Primary Care: Understanding Its Value |publisher=Radcliffe Medical Press |location=Abingdon |year=2006 |pages= |isbn=1-85775-724-6 |oclc= |doi=}}[http://www.acpjc.org/Content/147/3/issue/ACPJC-2007-147-3-A11.htm Book review]</ref><ref name="isbn1-85775-855-2">{{cite book |author=Holt, Tim A | title=Complexity for Clinicians |publisher=Radcliffe Medical Press |location=Abingdon |year=2004 |pages= |isbn=1-85775-855-2 |oclc= |doi=}} [http://www.mja.com.au/public/bookroom/2007/zwar/zwar.html Book review], [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1463117 ACP Journal Club Review]</ref> and education<ref name="pmid11588088">{{cite journal |author=Fraser SW, Greenhalgh T |title=Coping with complexity: educating for capability |journal=BMJ |volume=323 |issue=7316 |pages=799–803 |year=2001 |pmid=11588088 |doi=}}</ref>.


====Complexity theory====
==Footnotes==
Complexity theory is proposed as further explaining the nature of medical knowledge.<ref name="isbn1-85775-724-6">{{cite book |author=Sweeney, Kieran  |title=Complexity in Primary Care: Understanding Its Value |publisher=Radcliffe Medical Press |location=Abingdon |year=2006 |pages= |isbn=1-85775-724-6 |oclc= |doi=}}[http://www.acpjc.org/Content/147/3/issue/ACPJC-2007-147-3-A11.htm Review]</ref><ref name="isbn1-85775-855-2">{{cite book |author=Holt, Tim A | title=Complexity for Clinicians |publisher=Radcliffe Medical Press |location=Abingdon |year=2004 |pages= |isbn=1-85775-855-2 |oclc= |doi=}} [http://www.mja.com.au/public/bookroom/2007/zwar/zwar.html Review], [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1463117 ACP Journal Club Review]</ref>
<small>
<references>


==References==
</references>
<references/>
</small>

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Evidence-based medicine is "the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients."[1] Alternative definitions are "the process of systematically finding, appraising, and using contemporaneous research findings as the basis for clinical decisions"[2] or "evidence-based medicine (EBM) requires the integration of the best research evidence with our clinical expertise and our patient's unique values and circumstances."[3] Better known as EBM, evidence based medicine has roots in clinical epidemiology and the scientific method, and emerged in the early 1990's in response to discoveries about variations and deficiencies[4] in medical care to help healthcare providers and policy makers evaluate the efficacy of different treatments.

Evidence-based practice is not restricted to medicine: dentistry, nursing and other allied health science are adopting "evidence-based medicine" as well as alternative medical approaches, such as acupuncture[5][6]. Evidence-Based Health Care or evidence-based practice extends the concept of EBM to all health professions, including management[7][8] and policy[9][10][11].

Classification

Two types of evidence-based medicine have been proposed:[12]

  • Evidence-based guidelines, EBM at the organizational or institutional level, which involves producing clinical practice guidelines, policy, and regulations;

Justification

Part of the justification for EBM is the unreliability about making clinical decisions using heuristics.[13][14]

Steps in EBM

See also Teaching evidence-based medicine
The 5 S search strategy[15]

Studies: original research studies that can be found using search engines like PubMed.

Synthesis: systematic reviews or Cochrane Reviews.

Synopses: in EBM journals, ACP Journal club etc. give brief descriptions of original articles and reviews as they appear .

Summaries: in EBM textbooks integrate the best available evidence from syntheses to give evidence-based management options for a health problem.

Systems: e.g. computerized decision support systems that link individual patient characteristics to relevant evidence.

Ask

To "ask" and formulate a well-structured clinical question, i.e. one that is directly relevant to the identified problem, and which is constructed in a way that facilitates searching for an answer. The question should have four 'PICO' elements[16][17]: the patient or problem (P); the medical intervention or exposure (e.g., a cause for a disease) (I); the comparison intervention or exposure (C); and the clinical outcomes (O). The better focused the question is, the more relevant and specific the search for evidence will be.[18]

Acquisition of evidence

Acquisition is difficult due to instability of medical knowledge[19][20][21][22][23][24]
Type of publication Durability
Primary publications
Highly cited studies major scientific journals[19] The results from one-third are refuted or attenuated within 15 years.
Original studies in hepatology[20] Half-life of truth was 45 years
Original studies in surgery[21] Half-life of truth was 45 years
Secondary publications
Systematic reviews[22] Median survival is 5.5 years.
7% may out of date when published
23% may be out of date within 2 years
Practice guidelines by the AHRQ[23] Half-life of truth was 5.8 years
Food and Drug Administration New Drug Approvals[24] 8% acquire a new black box warning. Half occur within 7 years
Food and Drug Administration New Drug Approvals[24] 3% withdrawn. Half occur within 2 years

The ability to "acquire" evidence, also called information retrieval, in a timely manner may improve healthcare.[25][26] Unfortunately, doctors may be led astray when acquiring information because of difficulties in selecting best articles[27], or because individual trials may be flawed or their outcomes may not be fully representative.[28]

Research conflicts on the ability of end-users of MEDLINE. One study found that users were almost as likely to misinterpret articles found as correctly interpret them.[28] A second study that was in vitro found that searching for evidence was helpful.[29]

One proposed structure for a comprehensive evidence search is the 5S search strategy,[15] and 6S[30] which starts with the search of "summaries" (textbooks). [31]

Appraisal of evidence

The U.S. Preventive Services Task Force (USPSTF) [32] grades its recommendations for treatments according to the strength of the evidence and the expected overall benefit (benefits minus harms). Its grades are:

A.— Good evidence that the treatment improves health outcomes, and benefits substantially outweigh harms.

B.— Fair evidence that the treatment improves health outcomes and that benefits outweigh harms.

C.— Fair evidence that the treatment can improve health outcomes but the balance of benefits and harms is too close to justify a general recommendation.

D.— Recommendation against routinely providing the treatment to asymptomatic patients. There is fair evidence that [the service] is ineffective or that harms outweigh benefits.

I.— The evidence is insufficient to recommend for or against routinely providing [the service]. Evidence that the treatment is effective is lacking, of poor quality, or conflicting and the balance of benefits and harms cannot be determined.

The USPSTF also grades the quality of the overall evidence as good, fair or poor:

Good: Evidence includes consistent results from well-designed, well-conducted studies in representative populations that directly assess effects on health.

Fair: Evidence is sufficient to determine effects on health outcomes, but its strength is limited by the number, quality, or consistency of the individual studies, generalizability to routine practice, or indirect nature of the evidence on health outcomes.

Poor: Evidence is insufficient to assess the effects on health outcomes because of limited number or power of studies, flaws in their design or conduct, gaps in the chain of evidence, or lack of information on important health outcomes.

To "Appraise" the quality of the evidence in a study is very important, as one third of the results of even the most visible medical research is eventually either attenuated or refuted.[19] There are many reasons for this[33]; two of the most common being publication bias[34] and conflict of interest[35] (see article on Medical ethics). These two problems interact, as conflict of interest often leads to publication bias.[36][34] Complicating the appraisal process further, many (if not all) studies contain some design flaws, and even when there are no clear methodological flaws, any outcome of a test that is evaluated by statistical test has a margin of error: this means that some positive outcomes will be "false positives".

Often, only the abstract of an article will be read,[37] but many abstracts contain errors.[38] These are usually errors of omission rather than contradiction, but abstracts often over-emphasise positive findings and neglect to mention limitations.

When abstracts are read, readers may be biased [39] and make illogical conclusions[40].

The initial steps in reading an article are determining what the article's conclusion and whether its conclusion, if valid, is important.[41]

Overall risk in the population in a study can be assessed by examining outcome rr prevalence rates in the control groups.[42]

Automated text mining can help assess the quality of an article.[43]

"Levels of evidence" are used for describing the strength of a research study.[44][45] The Equator network is a collection of standards to improve the reporting of health research. An example is the Consort statement for the reporting of randomized controlled trials.

Guides exist for assessing a body of literature; these are discussed below, Assessing a body of research evidence.

Common threats to validity

Publication bias
Publication bias is "the influence of study results on the chances of publication [in academic journals] and the tendency of investigators, reviewers, and editors to submit or accept manuscripts for publication based on the direction or strength of the study findings. Publication bias has an impact on the interpretation of clinical trials and meta-analyses. Bias can be minimized by insistence by editors on high-quality research, thorough literature reviews, acknowledgment of conflicts of interest, modification of peer review practices, etc."[46]

Conflict of interest

For more information, see: Conflict of interest.

The presence of a conflict of interest has many effects in medical publishing.

Statistical analysis
Common problems include small sample sizes in subgroup analyses[47], problems of "multiple comparisons" when several outcomes are being assessed, and biasing of study populations by selection criteria.

Problems may arise from interim analyses of randomized controlled trials which may lead to exaggerated estimations of treatment effects.[48][49] [50]

Statistical significance:
The statistical significance of the outcome of a study is often summarized by a "P-value" that expresses the likelihood that an observed difference between treatment groups reflects a true difference in treatment effect; the P value is a calculation of the chance that the observed difference reflects the chance outcome of random sampling. Some have argued that focusing on P values neglects other important sources of knowledge and information that should be used to assess the likely efficacy of a treatment [51] In particular, some argue that the P-value should be interpreted in light of how plausible is the hypothesis based on the totality of prior research and physiologic knowledge.[52][51][53] Bayesian inference formalizes this approach to statistical significance.

Application

It is important to "apply" the best practices found to the correct situation. One common problem in applying evidence is that both patients and healthcare professionals often have difficulties with health numeracy and probabilistic reasoning.[54] Another problem is successful clinical reasoning at the bedside.[55] Successful reasoning is associated with the use of pattern matching [56][57] and recognizing clinical findings that are "pivot" or specific to certain diseases[57]. A third problem is to identify exactly which patients will benefit from the new practices. Extrapolating study results to the wrong patient populations (over-generalization)[58][59][60] and not applying study results to the correct population (under-utilization)[61][62] can both increase adverse outcomes.

The problem of over-generalizating study results may be more common among specialist physicians.[63] Two studies found specialists were more likely to adopt cyclooxygenase 2 inhibitor drugs before the drug rofecoxib was withdrawn by its manufacturers because of its unanticipated adverse effects [64][65]. One of the studies went on to state:

"using COX-2s as a model for physician adoption of new therapeutic agents, specialists were more likely to use these new medications for patients likely to benefit but were also significantly more likely to use them for patients without a clear indication".[65]

Similarly, orthopedists provide more expensive care for back pain, but without measurably increased benefit compared to other types of practitioners.[66] Some of the reason that subspecialists may be more likely to adopt inadequately studied innovations is that they read from a spectrum of journals that have less consistent quality.[67] Articles from specialty journals have been noted to persist in supporting claims in the medical literature that have been refuted.[68]

The problem of under-utilizing study results may be more common when physicians are practising outside their expertise. For example, specialist physicians are less likely to under-utilize specialty care[69][70], while primary care physicians are less likely to under-utilize preventive care[71][72].

Metrics used in EBM

Diagnosis
Causation
Relative measures
Absolute measures
Health policy
For more information, see: Cost-benefit analysis.
  • Cost per year of life saved[75]
  • Cost of Preventing an Event (COPE)[76]. For example, to prevent a major vascular event n a high-risk adult , the number needed to treat is 19, the number of years of treatment are 5, and the daily cost of the generic drug is 68 cents. The COPE is 19 * 5 * ( 365 * .68) which equals $23,579 in the United States.
  • Years (or months or days) of life saved. "A gain in life expectancy of a month from a preventive intervention targeted at populations at average risk and a gain of a year from a preventive intervention targeted at populations at elevated risk can both be considered large."[77]

Original research studies: levels of evidence

'Levels of evidence' were first proposed in 1979 bye the Canadian Task Force on the Periodic Health Examination[44] then modified by the American College of Chest Physicians[78][79] to create a framework for judging the strength of research. An example of levels of evidence is, based on prior work[45]:

These levels of evidence have been criticized as only representing one of two views of medical science.[81] Vandenbroucke proposes that the two views of medical research are:

  1. Evaluation of interventions. In this view, the randomized controlled trial is most important.
  2. Discovery and explanation. In this view, the randomized controlled trial is not supreme and observational studies, subgroup analyses, and secondary analyses are important.

In practice, randomized controlled trials are available to support only 21%[82] to 53%[83] of principal therapeutic decisions.[84] Due to this, evidence-based medicine has evolved to accept lesser levels of evidence when randomized controlled trials are not available.[85]

The Grade Working Group recognizes that assessing medical evidence involves attention to other dimensions than study design, and expanded upon the levels of evidence in 2004.[86][87] These dimensions include: study design; study quality; consistency of study results; and directness (e.g. how close does the research study mirror clinical practice)

Summarizing the evidence

Assessing a body of research evidence

Several systems have been proposed to assess whether a body of research evidence establishes causality.

Koch's postulates[88]
  • "The bacterium must be present in every case of the disease."
  • "The bacterium must be isolated from the diseased host and grown in pure culture."
  • "The specific disease must be reproduced when a pure culture of the bacterium is inoculated into a healthy susceptible host."
  • "The bacterium must be recoverable from the experimentally infected host."

In the 1880's Koch proposed postulates (Koch's Postulates) that suggest association.[89] However, even though the postulates focus on establishing casuality among infections diseases, examples have emerged that violate his postulates.[88]

Bradford Hill criteria[90]
  • Strength or magnitude of association?
  • Consistency of association across studies?
  • Specificity of association?
  • Temporality of association?
  • Plausibility based on biological knowledge?
  • Biological gradient: or dose-response relationship?
  • Coherence? Does the proposed association explain other observations?
  • Experimental evidence?
  • Analogy?

The Bradford Hill criteria were proposed in 1965 in response to studies of the association between tobacco and lung cancer:[90]

More explicit methods have been proposed by groups such as the U.S. Preventive Services Task Force (USPSTF) (see yellow text box above), the American College of Chest Physicians[78][79] and the Grade Working Group[91] The Grade Working Group combines the quality of research studies with their clinical relevance.[86] For example, this allows comparing a randomized control trial in a population that is not exactly like the population of interest versus a cohort study that is from a relevant population. The concept that there are multiple dimensions in assessing evidence has been expanded to a proposal that assessing evidence is not a linear process, but is circular.[92]

Diamond has proposed a method using Bayesian beliefs for assessing medical evidence that categorizes beliefs similarly to how evidence is assessed in the legal system.[93]

The legal system
See Medical malpractice#Standard of care

Systematic review

For more information, see: Systematic review.

A systematic review is a summary of healthcare research that involves a thorough literature search and critical appraisal of individual studies to identify the valid and applicable evidence. It often, but not always, uses appropriate techniques (meta-analysis) to combine studies, and may grade the quality of the particular pieces of evidence according to the methodology used, and according to strengths or weaknesses of the study design. While many systematic reviews are based on an explicit quantitative meta-analysis of available data, there are also qualitative reviews which nonetheless adhere to the standards for gathering, analyzing and reporting evidence.

Clinical practice guidelines

For more information, see: Clinical practice guideline.

Clinical practice guidelines are defined as "Directions or principles presenting current or future rules of policy for assisting health care practitioners in patient care decisions regarding diagnosis, therapy, or related clinical circumstances. The guidelines may be developed by government agencies at any level, institutions, professional societies, governing boards, or by the convening of expert panels. The guidelines form a basis for the evaluation of all aspects of health care and delivery."[94]

Incorporating evidence into clinical care

see also Teaching evidence-based medicine

Medical informatics

For more information, see: Medical informatics.

Practicing clinicians cite the lack of time for keeping up with emerging medical evidence that may change clinical practice.[95] Medical informatics is an essential adjunct to EBM, and focuses on creating tools to access and apply the best evidence for making decisions about patient care.[3] Before practicing EBM, informaticians (or informationists) must be familiar with medical journals, literature databases, medical textbooks, practice guidelines, and the growing number of other evidence-based resources, like the Cochrane Database of Systematic Reviews and Clinical Evidence.[95] Similarly, for practicing medical informatics properly, it is essential to have an understanding of EBM, including the ability to phrase an answerable question, locate and retrieve the best evidence, and critically appraise and apply it.[96][97]

Health care quality assurance

For more information, see: Health care quality assurance.

Criticisms of EBM

Statue of David Hume. "Man is a reasonable being; and as such, receives from science his proper food and nourishment: But so narrow are the bounds of human understanding, that little satisfaction can be hoped for in this particular..." Hume recognised clearly the difficulties in gaining a general understanding merely by accumulating observations.

There are a number of criticisms of EBM.[98][99]

Excessive reliance on empiricism and deduction

EBM has been criticized as an attempt to define knowledge in medicine in the same way that was done unsuccessfully by the logical positivists in epistemology, "trying to establish a secure foundation for scientific knowledge based only on observed facts" [100]and not recognizing the fallible nature of knowledge in general.[101] The problem of relying on empiric evidence as a foundation for knowledge was recognized over 100 years ago and is known as the "Problem of Induction" or "Hume's Problem".[102] Alternative logic is induction and abduction.[103]

Inability to individualize for each patient

A general problem with EBM is that it seeks to make recommendations for treatment that (on balance) are likely to provide the best treatment for most patients. However what is the best treatment for most patients is not necessarily the best treatment for a particular individual patient. The causes of disease, and the patient responses to treatment all vary considerably, and are affected for example by the individual's genetic make-up, their particular history, and by factors of individual lifestyle. To take these properly into account requires the clinical experience of the treating physician, and over-reliance upon recommendations based upon statistical outcomes of treatments given in a standardised way to large populations may not always lead to the best care for a particular individual.

Ulterior motives

An early criticism of EBM is that it will be a guise for rationing resources or other goals that are not in the interest of the patient.[104][105] In 1994, the American Medical Association helped introduce the "Patient Protection Act" in Congress to reduce the power of insurers to use guidelines to deny payment for a medical services.[106] As a possible example, Milliman Care Guidelines state they produce "evidence-based clinical guidelines since 1990".[107] In 2000, an academic pediatrician sued Milliman for using his name as an author on a practice guidelines that he stated were "dangerous" [108][109][110] A similar suit disputing the origin of care decisions at Kaiser has been filed.[111] The outcomes of both suits are not known.

Conversely, clinical practice guidelines by the Infectious Disease Society of America are being investigated by Connecticut's attorney general on grounds that the guidelines, which do not recognize a chronic form of Lyme disease, are anticompetitive.[112][113]

EBM not recognizing the limits of clinical epidemiology

EBM is a set of techniques derived from clinical epidemiology, but a common criticism is that epidemiology can show association but not causation. While clinical epidemiology has its role in inspiring clinical decisions if it is complemented with testable hypotheses on disease,[114] many critics consider that EBM is a form of clinical epidemiology which became so common in health care systems, and imposed such an empiricist bias on medical research, that it has undermined the notion of causal inference in clinical practice.[115] It is argued that it has even become condemnable to use common sense,[116] as was cleverly illustrated in a systematic review of randomized controlled trials studying the effects of parachutes against gravitational challenges (free falls).[117]

Lorenz butterfly showing two attractors in a complex, chaotic system. See complexity science.

Complexity science

For more information, see: complexity science.

Complexity science and chaos theory are proposed as further explaining the nature of medical knowledge[118][119] and education[120].

Footnotes

  1. ↑ Sackett DL et al. (1996). "Evidence based medicine: what it is and what it isn't". BMJ 312: 71–2. PMID 8555924. [e]
  2. ↑ Evidence-Based Medicine Working Group (1992). "Evidence-based medicine. A new approach to teaching the practice of medicine. Evidence-Based Medicine Working Group". JAMA 268: 2420–5. PMID 1404801. [e]
  3. ↑ 3.0 3.1 Glasziou, Paul; Strauss, Sharon Y. (2005). Evidence-based medicine: how to practice and teach EBM. Elsevier/Churchill Livingstone. ISBN 0-443-07444-5. 
  4. ↑ Thier SL, Yu-Isenberg KS, Leas BF et al (2008). "In chronic disease, nationwide data show poor adherence by patients to medication and by physicians to guidelines". Manag Care 17: 48-52, 55-7. PMID 18361259. [e]
  5. ↑ Manheimer E et al. (2007). "Meta-analysis: acupuncture for osteoarthritis of the knee". Ann Intern Med 146: 868–77. PMID 17577006. [e]
  6. ↑ Assefi NP et al. (2005). "A randomized clinical trial of acupuncture compared with sham acupuncture in fibromyalgia". Ann Intern Med 143: 10–9. PMID 15998750. [e]
  7. ↑ Clancy CM, Cronin K (2005). "Evidence-based decision making: global evidence, local decisions". Health Affairs (Project Hope) 24: 151–62. DOI:10.1377/hlthaff.24.1.151. PMID 15647226. Research Blogging.
  8. ↑ Shojania KG, Grimshaw JM (2005). "Evidence-based quality improvement: the state of the science". Health Affairs (Project Hope) 24: 138–50. DOI:10.1377/hlthaff.24.1.138. PMID 15647225. Research Blogging.
  9. ↑ Fielding JE, Briss PA (2006). "Promoting evidence-based public health policy: can we have better evidence and more action?". Health Affairs (Project Hope) 25: 969–78. DOI:10.1377/hlthaff.25.4.969. PMID 16835176. Research Blogging.
  10. ↑ Foote SB, Town RJ (2007). "Implementing evidence-based medicine through medicare coverage decisions". Health Affairs (Project Hope) 26 (6): 1634–42. DOI:10.1377/hlthaff.26.6.1634. PMID 17978383. Research Blogging.
  11. ↑ Fox DM (2005). "Evidence of evidence-based health policy: the politics of systematic reviews in coverage decisions". Health Affairs (Project Hope) 24: 114–22. DOI:10.1377/hlthaff.24.1.114. PMID 15647221. Research Blogging.
  12. ↑ 12.0 12.1 Eddy DM (2005). "Evidence-based medicine: a unified approach". Health Affairs (Project Hope) 24: 9-17. DOI:10.1377/hlthaff.24.1.9. PMID 15647211. Research Blogging.
  13. ↑ Aberegg SK, O'Brien JM (2009). "The normalization heuristic: an untested hypothesis that may misguide medical decisions.". Med Hypotheses 72 (6): 745-8. DOI:10.1016/j.mehy.2008.10.030. PMID 19231086. Research Blogging.
  14. ↑ McDonald CJ (1996). "Medical heuristics: the silent adjudicators of clinical practice.". Ann Intern Med 124 (1 Pt 1): 56-62. PMID 7503478.
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  16. ↑ Richardson WS, Wilson MC, Nishikawa J, Hayward RS (1995 Nov-Dec). "The well-built clinical question: a key to evidence-based decisions.". ACP J Club 123 (3): A12-3. PMID 7582737.
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  18. ↑ Schardt C, Adams MB, Owens T, Keitz S, Fontelo P (2007). "Utilization of the PICO framework to improve searching PubMed for clinical questions". BMC Med Inform Decis Mak 7: 16. DOI:10.1186/1472-6947-7-16. PMID 17573961. PMC 1904193. Research Blogging.
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  111. ↑ Colliver, V (1/07/2002). Lawsuit disputes truth of Kaiser Permanente ads. San Francisco Chronicle. Retrieved on 2007-11-14.
  112. ↑ Warner, S (2/7/2007). The Scientist : State official subpoenas infectious disease group. Retrieved on 2007-11-14.
  113. ↑ Gesensway, D (2007). ACP Observer, January-February 2007 - Experts spar over treatment for 'chronic' Lyme disease. Retrieved on 2007-11-14.
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  116. ↑ Michelson J (2004). "Critique of (im)pure reason: evidence-based medicine and common sense". J Evaluation Clin Pract 10: 157–61. DOI:10.1111/j.1365-2753.2003.00478.x. PMID 15189382. Research Blogging.
  117. ↑ Smith GC, Pell JP (2003). "Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials". BMJ 327: 1459–61. DOI:10.1136/bmj.327.7429.1459. PMID 14684649. Research Blogging.
  118. ↑ Sweeney, Kieran (2006). Complexity in Primary Care: Understanding Its Value. Abingdon: Radcliffe Medical Press. ISBN 1-85775-724-6. Book review
  119. ↑ Holt, Tim A (2004). Complexity for Clinicians. Abingdon: Radcliffe Medical Press. ISBN 1-85775-855-2.  Book review, ACP Journal Club Review
  120. ↑ Fraser SW, Greenhalgh T (2001). "Coping with complexity: educating for capability". BMJ 323 (7316): 799–803. PMID 11588088. [e]

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