title: Implications of the pulmonary artery to ascending aortic ratio in patients with relatively mild chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Identifying markers for predicting the course and outcome of chronic obstructive pulmonary disease (COPD) remains important. The relative pulmonary artery enlargement to aorta ratio (PA-A ratio), which is measured using computed tomography (CT), is a reported predictor for COPD exacerbation and mortality. However, little is known about the implications of the PA-A ratio in patients with mild COPD.
  
  
  METHODS
  We investigated the utility of the PA-A ratio as a biomarker in patients with relatively mild COPD. A total of 131 patients with mild to moderate COPD [post-bronchodilator forced expiratory volume in 1 sec (FEV1)/forced vital capacity (FVC) 61.6±6.4, mean post-bronchodilator FEV1 83%±17.8% of predicted value] were selected from a Korean COPD cohort (from 2012 until the end of 2014) and analyzed retrospectively. We determined the correlation between the PA-A ratio and clinical parameters using a linear regression model.
  
  
  RESULTS
  The COPD assessment test (P=0.04), FEV1 (P=0.03), and a history of exacerbation in the last year (P=0.03) were significant factors in the univariate linear regression analysis. Post-bronchodilator FEV1 was most significantly associated with the PA-A ratio in the multivariate analysis (P=0.01).
  
  
  CONCLUSIONS
  The PA-A ratio evaluated by CT imaging was independently correlated with a representative pulmonary function factor (FEV1) in patients with relatively mild COPD. The results suggest that the PA-A ratio may be an important biomarker for clinical outcome in patients with mild COPD.
authors: Department of School of Medicine, Kangwon National University, Chuncheon, Korea ;
authors: Cho Rom
authors: CR
authors: Hahm
authors: Department of Respiratory Center, Kangwon National University Hospital, Chuncheon, Korea ;
authors: Myoung Nam
authors: MN
authors: Lim
authors: Department of Radiology, Kangnam Sacred Heart Hospital, Hallym University Medical Center, Seoul, Korea ;
authors: Hee Yeong
authors: HY
authors: Kim
authors: Stem Cell Institute, Kangwon National University, Chuncheon, Korea ;
authors: Seok-Ho
authors: SH
authors: Hong
authors: Department of Internal Medicine and Environmental Health Center, Kangwon National University Hospital, Chuncheon, Korea.
authors: Seon-Sook
authors: SS
authors: Han
authors: Department of Internal Medicine and Environmental Health Center, Kangwon National University Hospital, Chuncheon, Korea.
authors: Seung-Joon
authors: SJ
authors: Lee
authors: Department of Internal Medicine and Environmental Health Center, Kangwon National University Hospital, Chuncheon, Korea.
authors: Woo Jin
authors: WJ
authors: Kim
authors: Department of Internal Medicine and Environmental Health Center, Kangwon National University Hospital, Chuncheon, Korea.
authors: Yoonki
authors: Y
authors: Hong
keywords: Biomarker; chronic obstructive lung disease (COPD); computed tomography (CT); exacerbation; relative pulmonary artery to aorta ratio (PA-A ratio)