Healthcare Resource Utilisation and Costs of Mepolizumab Initiation: A 5‐Year National Cohort Analysis
Authors: Arnaud Bourdin, Erika Nogue, Carey M. Suehs, Nicolas Malafaye, Joana Pissarra, Isabelle Vachier, Engi Ahmed, Nicolas Molinari
Journal: Allergy (2025)

Mepolizumab is effective as an add-on treatment for severe eosinophilic asthma (SEA) [1-3], but its cost is a drawback, with some countries restricting its use to the most severe patients. We aimed to describe changes in costs and HCRU (Healthcare Resource Utilisation) in a comprehensive, nation-wide population of patients under mepolizumab with at least 12-months of follow-up. We analysed data from the 6139 adult compliant SEA patients who initiated mepolizumab treatment nationwide since approval and received at least eight injections during a 12-month follow-up period (Table 1). Following mepolizumab initiation (exposure period), medication costs greatly increased by 246% compared to the preceding year (baseline period), contributing to an overall rise in total costs by 83% (Figure 1A,B, Table S2). Costs increased for most patients (87%), whereas they decreased or remained unchanged for 13%. In particular, regarding patients already treated with biologicals (n = 1208), mepolizumab often replaced omalizumab or benralizumab, and medication costs barely increased (7.5%), whereas for the remaining patients, costs surged by 716% (Table S3). Hospital-related costs decreased by 20% after mepolizumab initiation, mainly due to a 57% reduction in asthma-related admissions (Figure 1B, Table S2). We also quantified costs associated with additional healthcare interventions, including imaging, devices, and other medical and paramedical support provided by outpatient clinics or community-level healthcare providers, which remained stable in both periods. In the baseline period, there was an even distribution of total costs. However, in the exposure period, the burden shifted (Figure 1A,B). Notably, the relative weight of medication costs increased from 36% to 69% of total costs. Oral corticosteroid (OCS) consumption decreased in the exposure period with a concomitant 24% reduction in OCS-related costs. The reduced OCS consumption meant 16.3% and 7.6% of patients improved their risk class from high risk to moderate or low, respectively (Figure 1C), with 1174 patients no longer in the 1 > g/year risk class. The mean reduction in annual individual OCS dose was 0.88 g (± 2.6) (p < 0.001). We provide nationwide real-world data from the French health care system describing increased direct costs and important clinical benefits following mepolizumab initiation over one-year. Measurable direct benefits encompassed reduced hospital expenses and glucocorticoid-sparing effects, as previously described [2, 4]. Nonetheless, these associated reduced costs did not compensate for the significant upfront medication costs in this initial 12-month period. The strong adherence to this new treatment suggests significant benefits of these effective therapies not captured here, such as symptom relief, improvement in comorbidities, higher work productivity, better asthma control and enhanced quality of life, in patients who have mostly exhausted existing treatment options (Figure S1). The effect of such an expensive drug on OCS consumption may seem disappointing and not justify such high costs. However, since OCS are reputedly inexpensive, significant clinical benefits are likely not reflected in huge cost differences. Also, most patients were probably still prescribed OCS as eventual rescue medications, which were not necessarily taken. The observed benefits within 12 months reported here are clinically relevant nonetheless. These initial reductions in OCS over 1 year could serve as indicators of future improvements, as OCS side effects are cumulative, mostly of delayed onset, and poorly reversible [5]. Longer follow-up studies are needed to fully ascertain mepolizumab's benefits in preventing and/or reducing OCS complications. New intervention strategies where biologicals are introduced before initiating OCS are now envisaged to prevent complications and bypass their poor reversibility [6]. Furthermore, longer-term studies could assess potential reductions of other asthma treatments (ICS LABA, LTRA), saving additional costs. This study analysed a national cohort of patients, comprised of all patients who initiated mepolizumab right after market availability, providing key insights on HCRU and informing future cost-effectiveness models. Extrapolation to other countries depends on their healthcare systems and price negotiation for such therapeutics. Still, the major shift in treatment costs for SEA patients towards medication, as biologicals become ubiquitous, raises discussions regarding cost distribution, negotiation and resource allocation within health systems. A.B., I.V., E.A. and N.Mo. were responsible for conceptualisation and methodology. E.N. and N.Ma. were responsible for data collection and formal analysis. All authors participated in data interpretation. C.M.S. and J.P. drafted the initial manuscript, and all authors critically read and contributed to the writing and critical reading of the manuscript. A.B. declares receiving grants or contracts, consulting fees, or support for lectures, presentations, meetings, and travel from Boeringher Ingelheim, Novartis, Astra Zeneca, Sanofi, Regeneron, GSK, Chiesi, AB science, Celltrion, Cipla, and Areteia. C.M.S. declares receiving institutional grants or contracts from Astra Zeneca and GSK, and personal fees for lectures, presentations or manuscript writing from Astra Zeneca. Remaining authors declare no conflicts of interest. The data that support the findings of this study are not publicly available due to privacy or ethical restrictions. Data S1. 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