Increase in Blood Eosinophil Count Over Time and Sputum IL8 are Associated with FEV1 Decline in Asthma

Background Asthma is associated with accelerated rate of FEV1 decline. ObjectiveTo determine predictive factors associated with accelerated FEV1 decline in adult asthma and evaluate sputum cytokines as potential biomarkers for airflow decline. Methods We recruited 125 asthmatics evaluated at the asthma clinic of Li & egrave;ge and reevaluated them at least 5 years later. Clinical, functional and inflammatory characteristics were compared between patients with accelerated decline (FEV1 decline > 0.85% pred.y(-1)) and others. Predictive factors were highlighted with linear regression analysis. Sputum EGF, VEGF, FGF, IL5, IL8, TGF-beta, and IgE levels were measured in 58 of these patients at both visits by Human XL cytokine Luminex Performance assay and Elisa. Results Post-BD FEV1 decline was 0.06 +/- 2.44% pred.y-1 in the overall population. Median (IQR) time between visits was 66 (62 - 86) months. The multivariable analysis showed that an increase in blood eosinophils over time (Delta BEC) (Reg. Coef. (95%CI): 0.002 (0.001 to 0.004), p = 0.005)) and onset of asthma (0.04 (0.003 to 0.07), p = 0.036) were independently associated with FEV1 decline. IL8 levels measured at baseline were higher (499 (408-603) pg/ml, p = 0.0040) in patients with accelerated decline compared to others (143 (88-308) pg/ml). Conclusion In this study, we have confirmed that an increase in blood eosinophil counts over a follow-up of at least 5 years and later onset of asthma are associated with accelerated annual FEV1 decline. Moreover, high sputum IL8 levels could be a risk factor for accelerated decline in asthma patients.