Efficacy of sublingual immunotherapy in asthma:: systematic review of randomized-clinical trials using the Cochrane Collaboration method

Background: Sublingual immunotherapy (SLIT) is effective and safe in the treatment of allergic rhinitis. However, there is no meta-analysis in asthma treatment. Methods: The clinical efficacy of SLIT for asthma was evaluated through a systematic review with meta-analysis. MEDLINE (1966-2005), EMBASE (1974-2005), LILACS (1982-2005), and the Cochrane Library were searched for related literature in any language. Randomized-controlled clinical trials (RCT) on SLIT in asthma treatment for adults and children were selected. From 119 citations, 25 studies with 1706 patients were included in this meta-analysis. For each report, quality scores were assigned and data were extracted in relation to the outcomes analyzed: asthmatic symptoms, use of asthma medications, lung function, and bronchial provocation. Results: According to the Jadad quality method, 64% of the studies were assigned scores of 4 or 5. Immunotherapy was seen to significantly reduce asthma severity when parameter compositions were all analyzed by categorical outcomes. There was a nonsignificant reduction in asthma symptoms when analyzed using standardized mean differences. No severe reactions were observed. Conclusions: This meta-analysis found that SLIT is beneficial for asthma treatment albeit the magnitude of the effect is not very large. Moreover, it is a safe alternative to the subcutaneous route. More RCT with standardization of symptom scores and medications are needed in order to contribute further to this subject.