Sublingual immunotherapy vs placebo in the management of grass pollen-induced allergic rhinitis in adults: A systematic review and meta-analysis

Introduction Allergic rhinitis (AR) is a common inflammatory condition of the nasal mucosa affecting approximately 20% of the population worldwide. Current therapies include intranasal antihistamines, corticosteroids, subcutaneous and sublingual immunotherapy (SLIT). This review and meta-analysis assess the efficacy of SLIT in the management of grass pollen-induced AR in adults. Methods Ovid EMBASE, Ovid EBM Reviews, Cochrane Central Register of Controlled Trials, Ovid MedLine and PubMed were searched using the following terms: 'sublingual immunotherapy', 'SLIT', 'rhinitis', 'allergic rhinitis', 'rhinosinusitis' and 'rhino-conjunctivitis'. All included studies were double-blind, placebo-controlled and randomised trials. Primary outcome was symptom score and secondary outcome included quality of life and safety profile. Meta-analysis of symptom improvement was carried out. Results Six studies were identified with 979 subjects randomly allocated to SLIT and 992 to a placebo control. All studies reported an improvement in symptoms with SLIT, with five reaching statistical significance (P < .05). Four studies reported statistically significant improvement in quality of life (P < .05). Oral pruritus was the most common adverse event reported. The overall risk of bias was high in 50% of the studies. Conclusions Sublingual immunotherapy was a safe and effective treatment for grass pollen-induced AR in adults, and therefore, consideration should be given to its use for moderate-to-severe disease in the UK-wide population.