Study objectives: Multiple risk factors for mortality in patients with COPD have been described, but most studies have involved older, primarily male subjects. The purpose of this study was to determine the mortality rate and predictors of survival in subjects with severe, early onset COPD.
Design, setting, and participants: The cohort of 139 probands in the Boston Early-Onset COPD Study was recruited from lung transplant and general pulmonary clinics between September 1994 and July 2002. Subjects were < 53 years old, had an FEV1 of < 40% of predicted, did not have severe α1-antitrypsin deficiency, and had not undergone lung transplantation. The initial evaluation included a standardized respiratory questionnaire, spirometry, and a blood sample. A follow-up telephone interview was conducted between May and December 2002.
Measurements and results: Subjects were young (mean age at enrollment, 47.9 years) and had severe airflow obstruction (mean baseline FEV1, 19.4% predicted). A total of 72.7% of the subjects were women (p < 0.0001 [comparison to equal gender distribution]). The median estimated survival time was 7.0 years from the time of study enrollment, determined by the Kaplan-Meier method. The majority of deaths were due to cardiorespiratory illness. In a multivariable Cox proportional hazards model, adjusting for age, gender, and baseline FEV1, lifetime cigarette consumption (hazard ratio [HR], 1.20 [per 10 pack-years]; 95% confidence interval [CI], 1.02 to 1.40) and recent smoking status (HR, 2.50; 95% CI, 1.03 to 6.05) were both significant predictors of mortality.
Conclusion: In this cohort, recent smoking status predicted increased mortality independent of the effects of lifetime smoking intensity. Smoking cessation may confer a survival benefit even among patients with very severe COPD.