Survival in COPD

Kaplan-Meier survival curves for nonhypercapnic patients (type 1), reversible hypercapnics (type 2.1), and chronic hypercapnic patients (type 2.2). Survival among type 2.2 patients was significantly worse (P<0.05) by the Cox-Mantel test) than the other two groups. Percentages refer to proportion of patients who survived 5 years.