Adherence to Biologic Therapies is Associated with Improved Clinical Outcomes and Reduced Healthcare Resource Utilization in Patients with Severe Asthma in Japan.

Purpose: Biologic therapies have improved clinical outcomes and quality of life in patients with asthma, and treatment adherence is important for their effectiveness. This study evaluated 12-month adherence patterns for five asthma biologics approved in Japan and their impact on clinical and economic outcomes in patients with severe asthma. Methods: This non-interventional, cross-sectional, retrospective cohort study used Japan's Medical Data Vision database (June 2009-September 2024). Adults with severe asthma, ≥30 days of continuous enrollment pre-biologic initiation and ≥12 months of follow-up were included. Adherence was assessed using medication possession ratio (MPR). Group-based trajectory modeling (GBTM) characterized distinct adherence trajectories over time, providing insights into heterogeneous adherence behaviors and subgroup patterns. Impact of biologic adherence on exacerbations (defined by hospital admissions, emergency department visits or requiring oral/intravenous corticosteroids), healthcare resource utilization (HCRU) and pharmacy costs were analyzed descriptively. Results: Among 2904 eligible patients, average MPR was 62.6%-72.6% across the five biologics. Over 90% of patients received ≥1 follow-up dose of their biologic; with average MPR increased by 1%-6% among these patients versus the overall cohort. The GBTM analysis was conducted in 2531 patients without a biologic switch during follow-up, identifying seven distinct clusters with MPR ranging from 10.0% to 94.8%. Patients were also classified as adherent (41.1%), partially adherent (28.1%), minimally adherent (3.2%), or treatment discontinuation (27.6%), based on dosing frequency and intervals. Mean exacerbation rates defined by hospital admissions were low (0.02-0.08 events per patient/year). Exacerbations of any type typically increased with declining biologic adherence. Decreased adherence was generally associated with increased HCRU and higher asthma-related pharmacy costs, particularly when biologic costs were excluded. Conclusion: Biologic adherence was consistently associated with fewer exacerbations, reduced HCRU and lower asthma-related pharmacy costs (excluding biologic costs), reinforcing the importance of optimizing adherence in patients with asthma.