Comparing Racial Differences in Emphysema Prevalence Among Adults With Normal Spirometry: A Secondary Data Analysis of the CARDIA Lung Study

Background: Computed tomography (CT) imaging complements spirometry and may provide insight into racial disparities in respiratory health. Objective: To determine the difference in emphysema prevalence between Black and White adults with different measures of normal spirometry results. Design: Observational study using clinical data and spirometry from the CARDIA (Coronary Artery Risk Development in Young Adults) study obtained in 2015 to 2016 and CT scans done in 2010 to 2011. Setting: 4 U.S. centers. Participants: Population-based sample of Black and White adults. Measurements: Self-identified race and visually identified emphysema on CT in participants with different measures of normal spirometry results, calculated using standard race-specific and race-neutral reference equations. Results: A total of 2674 participants (485 Black men, 762 Black women, 659 White men, and 768 White women) had both a CT scan and spirometry available for analysis. Among participants with a race-specific FEV1 between 80% and 99% of predicted, 6.5% had emphysema. In this group, emphysema prevalence was 3.9-fold (95% CI, 2.1- to 7.1-fold; 15.5% vs. 4.0%) higher among Black men than White men and 1.9-fold (CI, 1.0- to 3.8-fold; 6.6% vs. 3.4%) higher among Black women than White women. Among participants with a race-specific FEV1 between 100% and 120% of predicted, 4.0% had emphysema. In this category, Black men had a 6.4-fold (CI, 2.2- to 18.7-fold; 13.9% vs. 2.2%) higher prevalence of emphysema than White men, whereas Black and White women had a similar prevalence of emphysema (2.6% and 2.0%, respectively). The use of race-neutral equations to identify participants with an FEV1 percent predicted between 80% and 120% attenuated racial differences in emphysema prevalence among men and eliminated racial differences among women. Limitation: No CT scans were obtained during the most recent study visit (2015 to 2016) when spirometry was done. Conclusion: Emphysema is often present before spirometry findings become abnormal, particularly among Black men. Reliance on spirometry alone to differentiate lung health from lung disease may result in the underrecognition of impaired respiratory health and exacerbate racial disparities.

Automated summary

There are differences in the prevalence of emphysema between Black and White adults with different measures of normal spirometry results, particularly among Black men.