Allergy Shots for Asthma

Injections of allergens (immunotherapy) are widely rescribed for patients with asthma, but little is known about their effectiveness.

The authors conducted a double-blind, placebo-controlled trial of multiple-allergen immunotherapy in allergic children with moderate-to-severe perennial (year-round) asthma. The children, who required daily medication for their asthma, were randomly assigned to receive subcutaneous injections of either a mixture of up to seven allergens or a placebo. Maintenance injections were continued for 18 months or longer. Medications were adjusted every two to three weeks on the basis of peak flow rates and symptoms. The principal outcome was the daily medication score (doses given). Bronchial sensitivity to metacholine (the concentration provoking a 20 percent decrease in the forced expiratory volume in one second [FEV1]) was measured twice yearly.

There were no significant differences between the study and placebo groups on average medication score nor on the number of days on which oral corticosteroids were used.

Partial or complete remission of asthma occurred in 31 percent of the immuno- therapy group and in 28 percent of the placebo group. There was no difference between the groups in the use of medical care, symptoms, or peak flow rates.

The authors concluded that immunotherapy with injections of allergens for over two years was of no discernible benefit in allergic children with perennial asthma who were receiving appropriate medical treatment.

(N Engl J Med 1997; 336:324-27)

Comment: The best results from immunotherapy are seen in individuals who have only one or two pollen or grass allergies. Unfortunately, as the number of allergens increases, the benefit of "allergy shots" decreases, particularly if one of the offenders is mold. - RA