Pulmonary function and airflow limitation in bronchiectasis: a case-control study of two independent cohorts

BACKGROUND: Bronchiectasis is a respiratory disease structurally characterised by irreversible airway dilatation. Functional impairments are also implicated in bronchiectasis, but the detailed changes in pulmonary function and the impact of clinical factors are yet to be examined. We analysed pulmonary function in patients with bronchiectasis based on their clinical features. METHODS: Two study cohorts-a multicentre bronchiectasis registry and health check-up examinees-were analysed. Airflow limitation was defined as forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) <0.7, and bronchiectasis severity was categorised using the number of involved lobes. RESULTS: Among 13 589 health check-up examinees, 606 (4.5%) had bronchiectasis; airflow limitation was more prevalent in those with bronchiectasis than in those without (17.3% vs 8.1%, p<0.001). Ever-smokers with bronchiectasis had the lowest FEV1, FEV1/FVC and FVC values, and the highest prevalence of airflow limitation. In the bronchiectasis registry (n=768), lung function parameters were worse in those with more involved lobes and Pseudomonas colonisation. Multivariable logistic regression analysis showed that bronchiectasis was independently associated with airflow limitation (OR 2.22 (95% CI 1.75 to 2.82)). CONCLUSIONS: Bronchiectasis is an independent risk factor for airflow limitation, and disease severity, smoking and Pseudomonas colonisation were each associated with worsening in pulmonary function.