Real-life compliance and persistence among users of subcutaneous and sublingual allergen immunotherapy

Background Subcutaneous allergen immunotherapy (SCIT) and sublingual allergen immunotherapy (SLIT) are safe and effective treatments of allergic rhinitis, but high levels of compliance and persistence are crucial to achieving the desired clinical effects. Objective Our objective was to assess levels and predictors of compliance and persistence among grass pollen, tree pollen, and house dust mite immunotherapy users in real life and to estimate the costs of premature discontinuation. Methods We performed a retrospective analysis of a community pharmacy database from The Netherlands containing data from 6486 patients starting immunotherapy for 1 or more of the allergens of interest between 1994 and 2009. Two thousand seven hundred ninety-six patients received SCIT, and 3690 received SLIT. Time to treatment discontinuation was analyzed and included Cox proportional hazard models with time-dependent covariates, where appropriate. Results Overall, only 18% of users reached the minimally required duration of treatment of 3 years (SCIT, 23%; SLIT, 7%). Median durations for SCIT and SLIT users were 1.7 and 0.6 years, respectively ( P