House dust mite immunotherapy in Germany: real-world adherence to a subcutaneous allergoid and a sublingual tablet

Abstract

Purpose: Allergen immunotherapy (AIT) is the only disease-modifying treatment for allergic rhinitis (AR) and asthma (AA) with increasing efficacy observed during the recommended 3 years of treatment and the potential for medium and long-term benefits. Adherence is of utmost importance to achieve these goals in real life. The objective of this study was to evaluate real-world adherence to house dust mite (HDM) AIT with a subcutaneous (SCIT) allergoid preparation and a sublingual (SLIT) tablet. Patients and methods: In this retrospective cohort analysis of a German longitudinal prescription database, patients receiving either a HDM-SCIT allergoid (n = 5677) or a HDM-SLIT tablet (n = 4720) were compared over a 3-year observation period. Study endpoints included adherence and days on therapy (DoT). Univariate statistical tests were used to assess the significance of the differences between SCIT vs. SLIT or the age classes. Results: Based on the number of reimbursed prescriptions SCIT adherence was 55.0% after 3 years while SLIT adherence was remarkably lower with 30.3% (p < 0.0001). The difference was observed already after first and second year of treatment and was in favor of SCIT with 93.2% vs. 63.2% and 70.9% vs. 43.4%, respectively. After 3 years, days on therapy were significantly higher in the SCIT group with 824 days vs. 491 days (p < 0.0001) showing significantly better data for all age groups. Adherence to SCIT was the highest in children, followed by adolescents and adults while the adherence to SLIT was higher in adults than adolescents. Conclusion: In this retrospective real-world cohort analysis in Germany, patients on subcutaneous AIT for HDM respiratory allergy achieved significantly higher adherence rates compared to the HDM-SLIT tablet over a 3-year treatment period. In addition, days on therapy were significantly higher for SCIT than for SLIT. It was shown that in real life significantly more patients receiving SCIT stay on the recommended treatment period of 3 years compared to SLIT subjects. This is important since effectiveness has been demonstrated to be linked with therapy duration.