Co-existence of COPD and bronchiectasis: A risk factor for a high ratio of main pulmonary artery to aorta diameter (PA:A) from computed tomography in COPD patients

Abstract

Background: Pulmonary vascular disease, especially pulmonary hypertension, is an important complication of COPD. Bronchiectasis is considered not only a comorbidity of COPD, but also a risk factor for vascular diseases. The main pulmonary artery to aorta diameter ratio (PA:A ratio) has been found to be a reliable indicator of pulmonary vascular disease. It is hypothesized that the co-existence of COPD and bronchiectasis may be associated with relative pulmonary artery enlargement (PA:A ratio >1). Methods: This retrospective study enrolled COPD patients from 2012 through 2016. Demo­graphic and clinical data were collected. Bhalla score was used to determine the severity of bronchiectasis. Patient characteristics were analyzed in two ways: the high (PA:A >1) and low (PA:A ≤1) ratio groups; and COPD with and without bronchiectasis groups. Logistic regression analysis was used to assess risk factors for high PA:A ratios. Results: In this study, 480 COPD patients were included, of whom 168 had radiographic bronchiectasis. Patients with pulmonary artery enlargement presented with poorer nutrition (albumin, 35.6±5.1 vs 38.3±4.9, P< 0.001), lower oxygen partial pressure (74.4±34.5 vs 81.3±25.4, P< 0.001), more severe airflow obstruction (FEV1.0, 0.9±0.5 vs 1.1±0.6, P=0.004), and a higher frequency of bronchiectasis (60% vs 28.8%, P< 0.001) than patients in the low ratio group. Patients with both COPD and bronchiectasis had higher levels of systemic inflammation (erythrocyte sedimentation rate, P< 0.001 and fibrinogen, P=0.006) and PA:A ratios (P< 0.001). A higher PA:A ratio was significantly closely correlated with a higher Bhalla score (r=0.412, P< 0.001). Patients with both COPD and bronchiectasis with high ratios presented higher levels of NT-proBNP (P< 0.001) and systolic pulmonary artery pressure (P< 0.001). Multiple logistic analyses have indicated that bronchiectasis is an independent risk factor for high PA:A ratios in COPD patients (OR =3.707; 95% CI =1.888–7.278; P< 0.001). Conclusion: Bronchiectasis in COPD has been demonstrated to be independently associated with relative pulmonary artery enlargement.