Effectiveness of subcutaneous versus sublingual immunotherapy for the treatment of allergic rhinoconjunctivitis and asthma: A systematic review

Background: Allergen-specific immunotherapy is widely used in the management of patients with allergic rhinoconjunctivitis and asthma, but the best route of delivery is unclear. Objective: We performed a systematic review of studies with head-to-head comparison of effectiveness and safety of subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) in the treatment of allergic rhinoconjunctivitis and asthma. Methods: MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials databases were searched through December 21, 2012. We included English language randomized controlled trials that enrolled patients with allergic rhinoconjunctivitis and/or asthma with head-to-head comparisons of SCIT with SLIT. Paired reviewers extracted detailed information from included articles on standardized forms and assessed the risk of bias in each article. Results: Eight trials compared the effectiveness and safety of SCIT and SLIT. The effectiveness of the 2 forms of immunotherapy in managing allergic asthma and rhinoconjunctivitis were reported in 4 and 6 clinical trials, respectively. Low-grade evidence supports greater effectiveness of SCIT than SLIT for asthma symptom reduction and also at reducing a combined measure of rhinitis symptoms and medication use. Moderate-grade evidence supports greater effectiveness of SCIT than SLIT for nasal and/or eye symptom reduction. All 8 trials reported on adverse events with an episode of anaphylaxis reported in a child treated with SCIT. Conclusion: Our review provides low-grade evidence to support that SCIT is superior to SLIT for reduction in asthma symptoms and moderate-grade evidence for reduction of allergic rhinoconjunctivitis. Additional studies are required to strengthen this evidence base for clinical decision making.