Real-World Effectiveness of Mepolizumab in Patients with Severe Asthma: An Examination of Exacerbations and Costs

Rationale: Results from clinical trials in patients with severe eosinophilic asthma have demonstrated that mepolizumab is well tolerated and is associated with improved asthma control as evidenced by reductions in both exacerbations and maintenance oral corticosteroid use, and improvements in lung function, asthma control, and quality of life. However, real-world data are lacking on the impact of mepolizumab treatment. Objective: To assess the effect of mepolizumab treatment on the rate of asthma exacerbations and asthma exacerbation-related costs in a real-world setting. Methods: This retrospective cohort study (GSK ID: 209017; HO-18-19168) analyzed data from patients with severe asthma >/=12 years of age at mepolizumab treatment initiation (index date) with >/=12 months pre- (baseline) and post-index (follow-up) data from a commercial claims database (patients were identified from November 1, 2015 to March 31, 2017). Asthma exacerbations (primary objective) and asthma exacerbation-related costs (secondary objective) in the baseline and follow-up periods were compared. Other analyses included the number of mepolizumab administrations and the use of concomitant asthma medications. Results: Data were analyzed from 346 patients. Mepolizumab significantly reduced the proportion of patients with any exacerbation and exacerbations requiring hospitalization, compared with baseline. Significant reductions in the rate of all exacerbations of 38.4% (from 2.68 to 1.65 events/patient/year; P<0.001) and of exacerbations requiring hospitalization of 72.7% (from 0.11 to 0.03 events/patient/year; P=0.004) were observed, compared with baseline. Mean total asthma exacerbation-related costs (excluding mepolizumab acquisition and administrative costs) per person were significantly lower during follow-up compared with baseline (P<0.05) and the use of asthma medications, including oral and inhaled corticosteroids, was also lower. Conclusion: This study confirms the clinical benefit observed in previous mepolizumab clinical trials and demonstrates that mepolizumab is effective in a real-world setting.