Predictors of Mortality in Patients with Stable COPD

OBJECTIVES  To determine which easily available clinical factors are associated with mortality in patients with stable COPD and if health-related quality of life (HRQoL) provides additional information. DESIGN  Five-year prospective cohort study. SETTING  Five outpatient clinics of a teaching hospital. PARTICIPANTS  Six hundred stable COPD patients recruited consecutively. MEASUREMENTS  The variables were age, FEV_1%, dyspnea, previous hospital admissions and emergency department visits for COPD, pack-years of smoking, comorbidities, body mass index, and HRQoL measured by Saint George’s Respiratory Questionnaire (SGRQ), Chronic Respiratory Questionnaire (CRQ), and Short-Form 36 (SF-36). Logistic and Cox regression models were used to assess the influence of these variables on mortality and survival. RESULTS  FEV_1%(OR: 0.62, 95% CI 0.5 to 0.75), dyspnea (OR 1.92, 95% CI 1.2 to 3), age (OR 2.41, 95% CI 1.6 to 3.6), previous hospitalization due to COPD exacerbations (OR 1.53, 1.2 to 2) and lifetime pack-years (OR 1.15, 95% CI 1.1 to 1.2) were independently related to respiratory mortality. Similarly, these factors were independently related to all-cause mortality with dyspnea having the strongest association (OR 1.54, 95% CI 1.1 to 2.2). HRQoL was an independent predictor of respiratory and all-cause mortality only when dyspnea was excluded from the models, except scores on the SGRQ were associated with all-cause mortality with dyspnea in the model. CONCLUSIONS  Among patients with stable COPD, FEV_1% was the main predictor of respiratory mortality and dyspnea of all-cause mortality. In general, HRQoL was not related to mortality when dyspnea was taken into account, and CRQ and SGRQ behaved in similar ways regarding mortality. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Sources of support: Grant no. 97/0326 from the Fondo de Investigación Sanitaria. Research Committee of Galdakao-Usansolo Hospital.