Efficacy and safety of allergen-specific immunotherapy for allergic asthma: a meta-analysis comparing sublingual and subcutaneous routes across allergen types and age groups

Purpose This meta-analysis aims to evaluate the efficacy and safety of allergen-specific immunotherapy (AIT) in treating allergic asthma.Methods A comprehensive search across PubMed, Cochrane Library, Embase and Web of Science was conducted. Randomized controlled trials (RCTs) evaluating AIT for allergic asthma were included. Data analysis was performed using RevMan 5.3, with evaluations for heterogeneity and publication bias. Subgroup analyses were stratified based on different treatment type, duration, age and allergen type (house dust mites vs. grass pollen).Results A total of 28 RCTs were included in the meta-analysis. AIT significantly improved asthma symptoms (p < 0.001), with SCIT showing greater efficacy than SLIT. Treatment duration and age did not significantly impact the outcomes. AIT was effective against both house dust mite and grass pollen allergies. It also notably improved medication scores (p < 0.001) and positively impacted FEV1 (p < 0.001). Regarding safety, AIT did not increase the total number of local side effects but significantly increased systemic reactions.Conclusion AIT is effective in improving asthma symptoms and reducing medication use, with subcutaneous immunotherapy being more efficacious than sublingual immunotherapy. The effectiveness varies by allergen type, with no substantial differences across age groups and treatment durations.