Predictors of 1-year mortality at hospital admission for acute exacerbations of chronic obstructive pulmonary disease

Background: Acute exacerbations of chronic obstructive pulmonary disease (AE-COPD) are related to high mortality, especially in hospitalized patients. Predictors for severe outcomes are still not sufficiently defined. Objectives: To assess the mortality rate and identify potential determinants of mortality in a cohort of patients hospitalized for AE-COPD. Methods: A retrospective, observational cohort study including all consecutive patients admitted between January 1, 2009, and April 1, 2010, for AE-COPD. Potential predictors were assessed at initial presentation at the emergency room. The primary outcome was mortality during 1-year follow-up. Univariate and multivariate time-to-event analyses using Cox proportional hazard models were employed for statistical analysis. Results: A total of 260 patients were enrolled in this study. Mean age was 70.5 +/- 10.8 years, 50.0% were male and 63.4% had severe COPD. The in-hospital mortality rate was 5.8% and the 1-year mortality rate was 27.7%. Independent risk factors for mortality were age [hazard ratio (HR) = 1.04; 95% confidence interval (CI) = 1.01-1.07], male sex (HR = 2.00; 95% CI = 1.15-3.48), prior hospitalization for AE-COPD in the last 2 years (HR = 2.56; 95% CI = 1.52-4.30), prior recorded congestive heart failure (HR = 1.75; 95% CI = 1.03-2.97), PaCO(2) >/=6.0 kPa (HR = 2.90; 95% CI = 1.65-5.09) and urea >/=8.0 mmol/l (HR = 2.38; 95% CI = 1.42-3.99) at admission. Conclusions: Age, male sex, prior hospitalization for AE-COPD in the last 2 years, prior recorded congestive heart failure, hypercapnia and elevated levels of urea at hospital admission are independent predictors of mortality within the first year after admission.