Effectiveness of subcutaneous versus sublingual immunotherapy for allergic rhinitis: current update

The effectiveness of subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) in treatment of patients suffering from allergic rhinitis have been evaluated in a number of randomized controlled trials, systematic reviews and meta-analyses conducted over the past few decades. Currently, there is a growing interest in evaluating comparative effectiveness of SCIT versus SLIT to identify whether one form of immunotherapy is better than the other. In this current update, we discuss pertinent systematic reviews that have addressed this concern.

The four systematic reviews identified in this update are the only reviews of effectiveness of SCIT versus SLIT for allergic rhinitis available in the literature. Through direct and indirect comparisons, these four reviews demonstrate that SCIT is better than SLIT in reducing symptoms of allergic rhinitis and rescue medication use in adults and children. However, there was no difference between the two forms of immunotherapy in reducing combined symptom-medication scores and improving quality of life. With regard to safety, SLIT had fewer systemic reactions when compared with SCIT.

The evidence of effectiveness of SCIT versus SLIT was principally derived from indirect comparisons and meta-regression. Additional randomized controlled trials of head-to-head comparisons of SCIT versus SLIT are required to strengthen this evidence base. Future research should focus on development of standardized outcome assessment, allergen dosing, content, and treatment regimes.