Anti-IL5 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 to 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 minimum 12 months apart, we compared characteristics of patients with and without decline (loss of post-BD FEV (% predicted)/year greater than zero) over time. Multiple linear regression was applied to study the factors independently associated with FEV decline. In the overall population (n=318), median (IQR) annual FEV decline was 0.27 (-4.22; 3.80) %predicted/year over a period of 23 (12-41) months. Asthma was less controlled at baseline in non-decliners than in decliners (53%). Lung function and residual volume at baseline were higher in the declining group. Decliners presented with increased bronchial reactivity (i.e. a lower PC20 Methacholine) at baseline. Twenty five percent of non-decliners were started on anti-IL5 for severe eosinophilic asthma (SEA) during the study, compared to 10% of decliners. The multivariable model suggested that ACQ score at baseline, late onset asthma and addition of anti-IL5 during follow-up were associated with lower FEV decline, independently from other variables such as evolution in exacerbations, smoking status, ICS or OCS dose, or add-on anti-IgE over time, while reversibility to salbutamol and higher FEV were associated with accelerated FEV decline. Add-on therapy with anti-IL5 in SEA was associated with an attenuated FEV decline. The causality of this observation should however be confirmed in future prospective controlled studies