IS ALLERGEN IMMUNOTHERAPY EFFECTIVE IN ASTHMA - A METAANALYSIS OF RANDOMIZED CONTROLLED TRIALS

A meta-analysis of clinical trials of allergen immunotherapy was under taken to assess the efficacy of this controversial form of therapy in asthma. A computerized bibliographic search revealed 20 randomized pla cebo controlled double-blind trials of allergen immunotherapy for asth ma. The results extracted included asthmatic symptoms, medication requ irements, lung function, and bronchial hyperreactivity (BHR). Categori cal outcomes were expressed as odds ratios and continuous outcomes as effect sizes. The combined odds of symptomatic improvement from immuno therapy with any allergen were 3.2 (95% CI 2.2 to 4.9). The odds for r eduction in medication after mite immunotherapy were 4.2 (95% CI 2.2 t o 7.9). The combined odds for reduction in BHR were 6.8 (95% CI 3.8 to 12.0). The mean effect size for any allergen immunotherapy on all con tinuous outcomes was 0.71 (95% CI 0.43 to 1.00), which would correspon d to a mean 7.1% predicted improvement in FEV, from immunotherapy. Alt hough the benefits of allergen immunotherapy could be overestimated be cause of unpublished negative studies, an additional 33 such studies w ould be necessary to overturn these results. Allergen immunotherapy is a treatment option in highly selected patients with extrinsic (''alle rgic'') asthma.