Background: COPD has been identified as an etiology or related disease of bronchiectasis, and bronchiectasis has been classified as a comorbidity of COPD. In this study, we investigated the prevalence of bronchiectasis in different phenotypes of COPD subjects and the correlation between bronchiectasis and different phenotypes, especially emphysema.
Methods: COPD patients were recruited from April 2012 to December 2015. The presence of bronchiectasis and related information were statistically analyzed. COPD subjects were separated into subgroups in two ways: COPD with and without bronchiectasis groups and emphysema-predominant (emphysema index, EI≥9.9%) and non-emphysema-predominant (EI<9.9%) groups.
Results: In total, 1,739 COPD patients were incorporated into the study, among which 140 cases (8.1%) were accompanied with radiological bronchiectasis. COPD patients with concomitant bronchiectasis presented worse pulmonary function (FEV₁% predicted, P <0.001), higher EI (15.0% vs 13.4%, P <0.001), and higher proportion of pulmonary hypertension and cor pulmonale (6.4% vs 2.4%, P =0.005 and 23.6% vs 16.1%, P =0.022) than patients without bronchiectasis. Of all the COPD patients, 787 with EI data were divided into emphysema-predominant (n=369) and non-emphysema-predominant groups (n=418). The proportion of bronchiectasis was 16.5% and 10.3% (P =0.01), respectively. Severity of bronchiectasis increased as the degree of airflow limitation (r =-0.371, P <0.001) and emphysema increased (r =0.226, P =0.021). After adjusting confounding factors, FEV₁% predicted (OR, 1.636; 95% CI, 1.219–2.197; P =0.001) and EI (OR, 1.993; 95% CI, 1.199–3.313; P =0.008) were significantly related with the presence of bronchiectasis in COPD patients.
Conclusion: The proportion of bronchiectasis is higher in emphysema-predominant COPD subjects. Emphysema measured by EI and FEV₁% predicted are independent predictors for bronchiectasis in COPD subjects, while the underlying mechanism deserves further investigation.
Keywords: bronchiectasis, COPD, computed tomography, emphysema, phenotype