title: Relationship between polycythemia and in-hospital mortality in chronic obstructive pulmonary disease patients with low-risk pulmonary embolism.
abstract: BACKGROUND
  Pulmonary embolism (PE) is frequent in subjects with chronic obstructive pulmonary disease (COPD) and associated with high mortality. This multi-center retrospective study was performed to investigate if secondary polycythemia is associated with in-hospital mortality in COPD patients with low-risk PE.
  
  
  METHODS
  We identified COPD patients with proven PE between October, 2005 and October, 2015. Patients in risk classes III-V on the basis of the PESI score were excluded. We extracted demographic, clinical and laboratory information at the time of admission from medical records. All subjects were followed until hospital discharge to identify all-cause mortality.
  
  
  RESULTS
  We enrolled 629 consecutive patients with COPD and PE at low risk: 132 of them (21.0%) with and 497 (79.0%) without secondary polycythemia. Compared with those without polycythemia, the polycythemia group had significantly lower forced expiratory volume in one second (FEV1) level (0.9±0.3vs. 1.4±0.5, P=0.000), lower PaO2and SpO2as well as higher PaCO2(P=0.03, P=0.03 and P=0.000, respectively). COPD patients with polycythemia had a higher proportion of arrhythmia in electrocardiogram (ECG) (49.5%vs. 35.7%, P=0.02), a longer hospital duration time (15.3±10.1vs. 9.7±9.1, P=0.001), a higher mechanical ventilation rate (noninvasive and invasive, 51.7%vs. 30.3%, P=0.04 and 31.0%vs. 7.9%, P=0.04, respectively), and a higher in-hospital mortality (12.1%vs. 6.6%, P=0.04). Multivariate logistic regression analysis revealed that polycythemia was associated with mortality in COPD patients with low-risk PE (adjusted OR 1.11; 95% CI, 1.04-1.66).
  
  
  CONCLUSIONS
  Polycythemia is an independent risk factor for all-cause in-hospital mortality in COPD patients with PE at low risk.
authors.affiliation: Department of Respiratory Medicine, West China Hospital of Sichuan University, Chengdu 610041, China;; Department of Respiratory Medicine, Sichuan Academy of Medical Science, Sichuan Provincial People's Hospital, University Hospital of Electronic Science & Technology of China, Chengdu 610072, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Guo
authors.affiliation: Radiology Department, University of Michigan Health System, Ann Arbor, MI 48109, USA.
authors.forename: Aamer Rasheed
authors.initials: AR
authors.lastname: Chughtai
authors.affiliation: Pneumology Group, Department of Integrated Traditional Chinese and Western Medicine, West China Hospital of Sichuan University, Chengdu 610041, China.
authors.forename: Hongli
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Department of Respiratory Medicine, Sichuan Academy of Medical Science, Sichuan Provincial People's Hospital, University Hospital of Electronic Science & Technology of China, Chengdu 610072, China.
authors.forename: Lingyun
authors.initials: L
authors.lastname: Gao
authors.affiliation: Department of Respiratory Medicine, Sichuan Academy of Medical Science, Sichuan Provincial People's Hospital, University Hospital of Electronic Science & Technology of China, Chengdu 610072, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Respiratory Medicine, Sichuan Academy of Medical Science, Sichuan Provincial People's Hospital, University Hospital of Electronic Science & Technology of China, Chengdu 610072, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Respiratory Medicine, Sichuan Academy of Medical Science, Sichuan Provincial People's Hospital, University Hospital of Electronic Science & Technology of China, Chengdu 610072, China.
authors.forename: Yuejian
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Respiratory Medicine, Sichuan Academy of Medical Science, Sichuan Provincial People's Hospital, University Hospital of Electronic Science & Technology of China, Chengdu 610072, China.
authors.forename: Zhenliang
authors.initials: Z
authors.lastname: Xie
authors.affiliation: Department of Respiratory Medicine, West China Hospital of Sichuan University, Chengdu 610041, China.
authors.forename: Weimin
authors.initials: W
authors.lastname: Li
keywords: Chronic obstructive pulmonary disease (COPD); mortality; polycythemia; pulmonary embolism (PE); pulmonary hypertension (PH)