The effect of airflow limitation on the cause of death in patients with COPD.

COPD is characterized by airflow limitation that is usually progressive. The present study investigated the cause of death and the effect of airflow limitation on all-cause mortality in COPD patients. A prospective cohort of 600 COPD patients were followed for 3 years. Patients in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 2 (32.7%), GOLD 3 (48.1%), or GOLD 4 (19.1%). Overall, 117 patients died (19.6%). Deaths were due to respiratory failure (29%), cardiovascular disease (25.6%), cancer (17.9%), infection (11%), gastrointestinal disease (9.4%), and other causes (6.7%). According to the Cox regression analysis, the following independent factors were related to mortality: age (years), hazards ratio (HR) 1.046 (confidence interval [CI] 95% 1.021, 1.072); current smoking status, HR 1.535 (CI 95% 1.003, 2.350); cancer, HR 7.172 (CI 95% 4.515, 11.395); cardiovascular disease, HR 2.623 (CI 95% 1.821, 3.778); severe airflow limitation (GOLD 4), HR 2.378 (CI 95% 1.605, 3.525); and highest quartile of acute exacerbations, HR 1.852 (CI 95% 1.236, 2.775). The present study shows that severe airflow limitation, current smoking status, the presence of cardiovascular disease, cancer, and a high frequency of acute exacerbations have an independent negative impact on the prognosis of COPD patients.