Blood eosinophils associate with reduced lung function growth in adolescent asthmatics

BACKGROUND AND OBJECTIVE: Some children with asthma have low lung growth, putting them at increased risk for COPD later in life. However, it is currently not clear who will experience this adverse growth pattern. We therefore investigated the predictive role of blood eosinophils as a Type 2 inflammation marker in lung growth, focusing on the presence and severity of asthma. METHODS: We investigated blood eosinophils and lung function growth (percentage predicted values) using linear mixed models in children and adolescents from two longitudinal cohorts. One cohort was hospital-based and consisted of asthmatic children at their first outpatient clinic visit after referral by the general practitioner (n=133, mean age 9.8) while the second was a general population-based birth cohort (PIAMA, asthma n=52 and non-asthma n=433, mean age 8.1). The hospital-based cohort had not been treated with inhaled corticosteroids (ICS) before referral. RESULTS: Subjects in the hospital-based asthma cohort had more severe asthma compared to the asthmatic subjects in the population-based cohort, defined by lower lung function levels and a higher prevalence of bronchial hyperresponsiveness. In the asthma cohort, higher blood eosinophil numbers were associated with less growth in FEV1 (estimated change in lung function per 1 unit increase in ln blood eosinophils (B): -0.66 %/year (95% confidence interval (CI): -1.11 to -0.20, p