Characterization of asthma by age of onset; a multi-database cohort study.

BACKGROUND: Asthma can occur at any age but the differences in patient characteristics between childhood-, adult- and late-onset asthma are not well understood. OBJECTIVE: To investigate differences in patients characteristics by age at asthma onset. METHODS: From five European electronic databases we created a cohort encompassing adult patients with doctor-diagnosed asthma in 2008-2013. Patients were categorized based on their age at asthma onset: childhood-onset (age at onset < 18 years), adult-onset (age at onset 18-40 years) and late-onset asthma (age at onset >=40 years). Comorbidities were assessed at study entry. For each characteristic and comorbidity, odds ratios (OR) and age- and sex-adjusted OR(ORadj) comparing asthma onset categories were estimated per database and combined in a meta-analysis using a random effect model. RESULTS: In total, 586,436 adult asthma patients were included, 81,691 had childhood-onset, 218,184 adult-onset and 286,561 late-onset asthma. Overall, 7.3% had severe asthma. Subjects with adult-onset compared to childhood-asthma had higher risks for overweight/obesity (ORadj 1.4, 95%CI 1.1-1.8) and lower risks for atopic disorders (ORadj 0.8, 95% CI 0.7-0.95). Patients with late-onset compared to adult-onset asthma had higher risks for nasal polyposis (ORadj 1.8, 95%CI 1.2-2.6), overweight/obesity (ORadj 1.3, 95%CI 1.2-1.4), gastro-oesophageal reflux disease (ORadj 1.4, 95%CI 1.2-1.7) and diabetes (ORadj 2.3, 95%CI 1.8-2.9). A significant association between late-onset asthma and uncontrolled asthma was observed (ORadj 2.8, 95%CI 1.7-4.5)). CONCLUSION: This international study demonstrates clear differences in comorbidities between childhood-, adult-, and late-onset asthma phenotypes in adults. Furthermore patients with late-onset asthma had more often uncontrolled asthma.