Real-world outcomes of mepolizumab for the treatment of severe eosinophilic asthma in Canada: an observational study

Background Mepolizumab, the first widely available anti-interleukin 5 biologic, targets eosinophilic inflammation and has been shown in clinical trials to reduce exacerbations, oral corticosteroid dependence, and healthcare utilization in patients with severe asthma. The impact of mepolizumab in a real-world, publicly funded healthcare setting is unknown. The objective of this study was to describe the demographics and clinical characteristics of real-world patients receiving mepolizumab, and to compare asthma-related outcomes and associated asthma-related costs before and during mepolizumab use. Methods This retrospective, observational study in Ontario, Canada, included patients initiating mepolizumab between February 2016 and March 2019. Patients were identified using the mepolizumab patient support program and linked to the Institute for Clinical Evaluative Sciences database of publicly accessed healthcare. Patient outcomes were obtained for 12 months pre- and post-mepolizumab initiation and compared. Results A total of 275 patients were enrolled in the overall patient support program cohort (mean [standard deviation] age 57.6 [13.5] years, mean [standard deviation] of the median per-patient eosinophil count 540.4 [491.9] cells/mu L). Mepolizumab was associated with reductions in asthma exacerbations (46.1%, P < 0.001) and in the number of asthma-related visits to general practitioners (40.2%, P < 0.001), specialists (27.2%, P < 0.001), and emergency departments (52.1%, P < 0.001). Associated costs were significantly lower post- versus pre-mepolizumab for asthma-related general practitioner and specialist visits, and for all-cause emergency department visits and hospital admissions. Conclusions In a real-world population of Canadian patients with severe asthma with an eosinophilic phenotype, the use of mepolizumab within a patient support program reduced asthma exacerbations and decreased asthma-related healthcare resource utilization and associated costs.