Sublingual or subcutaneous immunotherapy for seasonal allergic rhinitis: an indirect analysis of efficacy, safety and cost

RATIONALE, AIMS AND OBJECTIVES: The standard of preventive care for poorly controlled seasonal allergic rhinitis (AR) is subcutaneous immunotherapy (SCIT) with allergen extracts, administered in a physician's office. As an alternative to SCIT, sublingual immunotherapy (SLIT) is now an option for patients with seasonal AR. Oralair, a SLIT tablet containing freeze-dried allergen extracts of five grasses cocksfoot (Dactylis glomerata), meadow grass (Poa pratensis), rye grass (Lolium perenne), sweet vernal grass (Anthoxanthum odoratum) and timothy grass (Phleum pratense), and Grazax, a SLIT tablet containing a standardized extract of grass pollen allergen from timothy grass (P pratenase), are two such agents currently available in many countries. However, head-to-head comparative data are not available. In this study, an indirect comparison on efficacy, safety and cost was undertaken between Oralair, Grazax and SCIT. METHODS: A systematic review was conducted for double-blind placebo-controlled randomized trials evaluating Oralair, Grazax or SCIT in patients with grass-induced seasonal AR. Using placebo as the common control, an indirect statistical comparison between treatments was performed using meta regression analysis with active drug as the primary independent variable. An economic analysis, which included both direct and indirect costs for the Canadian setting, was also undertaken. RESULTS: Overall, 20 placebo-controlled trials met the study inclusion criteria. The indirect analysis suggested improved efficacy with Oralair over SCIT standardized mean difference (SMD) in AR symptom control = -0. 21; P = 0. 007 and Grazax (SMD = -0. 18; P = 0. 018). In addition, there were no significant differences in the risk of discontinuation due to adverse events between therapies. Oralair was associated with cost savings against year-round SCIT (2471), seasonal SCIT (948) and Grazax (1168) during the first year of therapy. CONCLUSIONS: Oralair has at least non-inferior efficacy and comparable safety against SCIT and Grazax at a lower annual cost.