The importance of cardiovascular disease for mortality in patients with COPD: a prognostic cohort study

Objective. To quantify the effect of cardiovascular determinants on mortality in patients with a GP's diagnosis of COPD. Methods. Four hundred and five patients aged >= 65 years with a diagnosis of COPD (244 with COPD by spirometry) were followed up for an average period of 4.2 (SD 1.4) years. Cox proportional hazard regression analyses with bootstrapping techniques were performed to identify independent predictors of all-cause mortality. Results. In multivariable analysis, all-cause mortality was best predicted by age [hazard ratio (HR) 1.05 [95% confidence interval (CI): 1.01-1.10] per year of age], angina pectoris on history taking [HR 2.32 (95% CI: 1.50-3.58)], airflow obstruction [HR 1.02 (95% CI: 1.01-1.03) per percentage decrease in level of forced expiratory volume in one second (FEV1) as % predicted] and C-reactive protein [HR 1.04 (95% CI: 1.02-1.05] per milligram per millilitre increase), respectively. The final model had a C statistic of 0.78 (95% CI: 0.72-0.83) after bootstrapping, and the calibration of the model was very good. The model performed similarly in the subgroup of 244 patients with COPD according to the GOLD criteria (post-dilatory FEV1/forced vital capacity < 0.70). Conclusions. Physicians should consider ischaemic heart disease in the clinical evaluation of any patient with a GP's diagnosis of COPD. Angina pectoris on history taking is a strong predictor of all-cause mortality in these patients and should be treated adequately to improve prognosis.