Anti–Interleukin-5 Therapy Is Associated with Attenuated Lung Function Decline in Severe Eosinophilic Asthma Patients From the Belgian Severe Asthma Registry

Asthmatics have accelerated lung function decline over time compared with healthy individuals.To evaluate risk factors for accelerated lung function decline.In a longitudinal analysis on severe asthmatics enrolled in the Belgian Severe Asthma Registry with at least 2 visits a minimum of 12 months apart, we compared characteristics of patients with and without decline (loss of post-bronchodilation forced expiratory volume in 1 s [FEV1] (% predicted)/y greater than zero) over time. Multiple linear regression was applied to study the factors independently associated with FEV1 decline.In the overall population (n = 318), median annual FEV1 decline was 0.27 (-4.22 to 3.80) % predicted/y over a period of 23 months (12-41 months). Asthma was less controlled at baseline in nondecliners than in decliners (53%). Lung function and residual volume at baseline were higher in the declining group. Decliners presented with increased bronchial reactivity (ie, a lower provocative concentration of methacholine causing a 20% fall in FEV1) at baseline. Twenty-five percent of nondecliners were started on anti-interleukin-5 (anti-IL-5) for severe eosinophilic asthma during the study compared with 10% of decliners. The multivariable model suggested that Asthma Control Questionnaire score at baseline, late-onset asthma, and addition of anti-IL-5 during follow-up were associated with lower FEV1 decline, independently from other variables such as evolution in exacerbations, smoking status, inhaled corticosteroids or oral corticosteroids dose, or add-on anti-immunoglobulin E over time, whereas reversibility to salbutamol and higher FEV1 were associated with accelerated FEV1 decline.Add-on therapy with anti-IL-5 in severe eosinophilic asthma was associated with an attenuated FEV1 decline. The causality of this observation should, however, be confirmed in future prospective controlled studies.