Adult Life-Course Trajectories of Lung Function and the Development of Emphysema: The CARDIA Lung Study

Background: Peak lung function and rate of decline predict future airflow obstruction and nonrespiratory comorbid conditions. Associations between lung function trajectories and emphysema have not been explored. Methods: Using data from the population-based CARDIA Study, we sought to describe the prevalence of visually ascertained emphysema at multiple time points and contextualize its development based upon participant's adult life course measures of lung function. There were 3171 men and women enrolled at a mean age of 25 years, who underwent serial spirometric examinations through a mean age of 55 years. Trajectories for the change in percent-predicted forced expiratory volume in one second (FEV₁) were determined by fitting a mixture model via maximum likelihood. Emphysema was visually identified on computed tomographic scans and its prevalence reported at mean ages of 40, 45, and 50 years. Results: We identified 5 trajectories describing peak and change in FEV₁: “Preserved Ideal,” “Preserved Good,” “Preserved Impaired,” “Worsening,” and “Persistently Poor.” Ever smokers comprised part of all 5 trajectories. The prevalence of emphysema was 1.7% (n = 46; mean age of 40 years), 2.5% (n = 67; mean age of 45 years), and 7.1% (n = 189; mean age of 50 years). Of those with emphysema at a mean age of 50 years, 18.0% were never smokers. Worsening and poor lung health trajectories were associated with increased odds of future emphysema independent of chronic tobacco smoke exposure (odds ratio 5.06; confidence interval, 1.84-13.96; odds ratio 4.85; confidence interval, 1.43-16.44). Conclusions: Lower peak and accelerated decline in FEV₁ are risk factors for future emphysema independent of smoking status.