Prevalence and Prognostic Significance of COPD in Adults Younger than 50 Years of Age.

Background: Identification of chronic obstructive pulmonary disease (COPD) diagnosed before 50 years of age ("young COPD") will help enable the study of preventive and therapeutic interventions for classically diagnosed COPD in later life. However, there remains uncertainty about the definition of young COPD and its prognostic significance.

Methods: We assessed the prevalence of young COPD, defined here as spirometric airflow obstruction plus symptoms of cough, phlegm, and dyspnea or 10 or more pack-years of smoking, among 18-to-49-year-old participants from four pooled, prospective U.S. cohorts. We evaluated the association of young COPD with premature mortality and respiratory and cardiovascular events over follow-up, using multivariable-adjusted proportional hazards models.

Results: Among 10,680 participants (median age, 40 years; 56.8% women; 41.7% Black; 51.1% unexposed to smoking), the prevalence of people meeting our case definition of young COPD was 4.5%. Compared with nonobstructed participants, the adjusted hazard ratio (an adjusted hazard ratio greater than unity indicates more incident cases) for participants with young COPD for death before 75 years of age was 1.43 (95% confidence interval [CI], 1.19 to 1.73; P<0.001); for incident hospitalization or death due to chronic lower respiratory disease, the adjusted hazard ratio was 2.56 (95% CI, 2.05 to 3.20); for coronary heart disease, the adjusted hazard ratio was 1.12 (95% CI, 0.85 to 1.47); and for heart failure, the adjusted hazard ratio was 1.72 (95%CI, 1.26 to 2.35). The hazards of the clinical outcomes in participants with simple obstruction (spirometric obstruction without symptoms and <10 pack-years; prevalence, 2.4%) were similar to those of nonobstructed participants.

Conclusions: Young COPD was present in 4.5% of adults under 50 years of age in the cohorts examined. The diagnosis was associated with premature mortality as well as respiratory and heart-failure events. (Funded by the National Heart, Lung, and Blood Institute and others.).