Risk factors analysis for one-year and long-term mortality in patients hospitalized for acute exacerbation of chronic obstructive pulmonary disease

Abstract

Objective: To identify the independent risk factors that predict one-year mortality and long-term mortality after hospitalization for acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Methods: A retrospective review of medical records and long-term follow-up were performed for inpatients with the first diagnosis of AECOPD at Beijing Chaoyang Hospital between January 2013 and December 2014. The follow-up was completed on March 1, 2018. Cox regression analysis was used to determine the independent risk factors for all-cause mortality of AECOPD patients. Results: A total of 890 AECOPD patients were enrolled. The average follow-up was 41 months (range 1-62). One-year mortality was 8.4% (75/890) and long-term mortality was 37.2% (331/890). In both scenarios, the main cause of death was respiratory disorders, and the next ones were cardiovascular and tumor disorders. The risk factors independently associated with one-year mortality included body mass index (HR 0.891, 95%CI 0.838-0.947, P<0.01), length of hospitalization (HR 1.031, 95%CI 1.019-1.042, P<0.01), lymphocyte count (HR 0.295, 95%CI 0.160-0.542, P<0.01), albumin (HR 0.935, 95%CI 0.880-0.994, P=0.031), atrial fibrillation (HR 2.220, 95%CI 1.038-4.747, P=0.040), and lung cancer (HR 5.865, 95%CI 2.608-13.192, P<0.01). The risk factors independently associated with long-term mortality included age (HR 1.046, 95%CI 1.031-1.062, P<0.001), body mass index (HR 0.939, 95%CI 0.914-0.964, P<0.01), length of hospitalization (HR 1.028, 95%CI 1.019-1.038, P<0.01), albumin (HR 0.957, 95%CI 0.929-0.986, P<0.01), partial pressure of carbon dioxide (HR 1.019, 95%CI 1.009-1.028, P<0.01), heart failure (HR 1.538, 95%CI 1.180-2.005, P=0.001), lung cancer (HR 3.443, 95%CI 2.033-5.830, P<0.01). However, blood eosinophil count (≥300 cells/μl) was not independently associated with one-year mortality (HR 0.892, 95%CI 0.309-2.579, P=0.834) and long-term mortality of COPD patients (HR 1.007, 95%CI 0.682-1.486, P=0.973). Conclusion: Old age, poor nutritional status, long length of hospitalization, cardiovascular disorders, lung cancer, low lymphocyte count and hypercapnia were independent risk factors for mortality of AECOPD patients.