CHADS2

CHADS2 is a scoring system for patients with atrial fibrillation to try and determine their risk of stroke, and therefore decide who should be treated with an anticoagulant.

It is an easily applied scoring system and each item scores one point (except for stroke, hence the 2)

• C—congestive heart failure
• H—hypertension
• A—age 75 or older
• D—diabetes mellitus
• S2—previous stroke or transient ischemic attack

giving a maximum score of 6.

The risk of stroke as a percentage per year is:

• 0—1.9%
• 1—2.8%
• 2—4.0%
• 3—5.9%
• 4—8.5%
• 5—12.5%
• 6—18.2%

As detailed in the respective JAMA and Circulation articles, a score of 0 is classified as low risk; 1-2, moderate risk; 3 or more, high risk. Based on this classification, the following treatment strategies were proposed by the authors:

• 0—Aspirin (325 mg/day most likely to offer benefit, although lower doses may be similarly efficacious)
• 1 to 2—Aspirin or Warfarin to INR 2.0-3.0, depending on factors such as patient preference
• 3 or more—Warfarin to INR 2.0-3.0 unless contraindicated (e.g., history of falls, clinically significant GI bleeding, inability to obtain regular INR screening)

The main criticism of the CHADS2 scoring system is that someone with atrial fibrillation and a previous history of stroke, but no other risk factors, is only classified as moderate risk, whereas that person is in fact at high risk of another stroke.