Perennial allergic rhinitis

Template:TOC-right Perennial allergic rhinitis is an inflammation of the mucous membrane of the nose with symptoms that persist throughout the year. The causes are usually air-borne allergens, particularly dusts, feathers, molds, animal fur, etc. It is distinguished from seasonal allergic disorders such as hay fever.

Allergic rhinitis itself is not life-threatening, although there are possible serious complications. It often coexists with asthma and can cause exacerbations. There is increasing correlation with this condition and adult-onset asthma. Recent studies indicate that atopy does not need to be present for rhinitis to be strongly associated with adult asthma.

Rhinitis does, however, have a significant impact on general quality of life, estimated to affect an overall 20% of the U.S. population, but 15% of Scandinavian men and 14% of women. Its prevalence is higher in children and lower in the geriatric age groups. It is unclear how much of the population difference is genetic and how much is environmental.

Medical history-taking is important, to determine if it is, indeed perennial, or due to a seasonal allergen. Even if it is perennial, a good history may reveal triggers such as house dust, offering the potential of ways to reduce exposure.

Occupational exposures are believed to be underestimated. Quite a number of food-related allergens can be significant, with exposures in agriculture, food processing, or food service.

Diagnosis

Diagnosis needs both to identify allergens, and determine their effects on the patient.

Allergen identification

History is apt to be revealing, but confirmation — and perhaps identification of unsuspected allergens — can come from in vitro radioallergosorbent test (RAST) testing and from in vivo skin testing. RAST is less precise, but faster and more comfortable for the patient. If immunotherapy is being considered, however, the precision of skin testing probably is necessary.

Treatment

There are three prongs of medical treatment, beginning with avoidance of the allergens. Drug and immune therapy are the other alternatives.

Avoidance

Preventing exposure requires a good knowledge of the cause. A very wide range of factors need to be considered. Economic factors can be very real; a patient may not have the resources to get air filtration systems or move to a better climate.

Some allergists refuse even to make an appointment with a patient that has a dog or cat, without even verifying if an animal allergy exists; given the human-animal bond, this can be challenged on ethical grounds. Other lifestyle adjustments, however, may be reasonable. If dust mites, a common allergen, are involved, removing carpets, and putting plastic covers over mattresses and pillows, can have a significant effect.

Pharmacologic

Intranasal corticosteroids, especially on a maintenance basis, can be highly effective, especially when allergy is truly limited to the nose and sinuses. Many patients respond to oral antihistamines; the second-generation type are apt to be nonsedating, but are more expensive and not always as effective as the first generation. It may be worth a trial of first-generation antihistamines, as they are not always sedating.

Some patients respond to intranasal antihistamines, anticholinergics, or antihistamines. Oral leukotriene antagonists help in some cases.

Decongestants are used more frequently than in the past, although there is still some concern with overuse of nasal sprays. Oral decongestants need to be used with care for some drug reactions, and with conditions such as uncontrolled hypertension.

Occasionally, a severe attack justifies a short course of an oral corticosteroid, typically tapering over 7-10 days.

Immunotherapy

Allergic desensitization can be highly effective, but it takes a long time (three to five years), may not show benefit for months, and the cost and convenience are factors. There is enough potential for reactions that it should be performed only by personnel trained and equipped to deal with complications up to, and including, anaphylactic shock. Desensitization is more effective for some antigens than others, and there may be local variations. Considering the range of factors takes clinical experience and a motivated patient.