Peak lung function and rate of decline predict future airflow obstruction and non-respiratory comorbid conditions. Associations between lung function trajectories and emphysema have not been explored.

Using data from the population-based CARDIA Study, a group of researchers, including Dr. Cora E. “Beth” Lewis, Chair of the Department of Epidemiology in the School of Public Health at the University of Alabama at Birmingham, 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. 3171 men and women were enrolled at a mean age of 25years and underwent serial spirometric examinations through a mean age of 55. 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.

The researchers 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), 2.5% (n=67; mean age of 45) and 7.1% (n=189; mean age of 50). Of those with emphysema at a mean age of 50, 18.0% were never smokers. Worsening and Poor lung health trajectories were associated with increased odds of future emphysema independent of chronic tobacco smoke.

The authors concluded that lower peak and accelerated decline in FEV1 are risk factors for future emphysema independent of smoking status.

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