Emphysema often present before abnormal spirometry, particularly in Black men

Emphysema is often present before spirometry findings become abnormal, with disproportionate rates seen in Black men, according to new findings published in Annals of Internal Medicine.

“According to this observational study of Black and white adults in the United States, a substantial proportion of middle-aged adults with ‘normal’ spirometry findings based on race-specific equations have emphysema on CT. This is disproportionately seen among Black men,” Gabrielle Y. Liu, MD, internist in the division of pulmonary and critical care medicine at Northwestern University Feinberg School of Medicine, and colleagues wrote. “This is also true when race-neutral equations are used to determine FEV₁ percent predicted; however, the use of race-neutral measures attenuates the racial disparity in emphysema prevalence among those with an FEV₁ between 80% and 120% of predicted. The increased rates of emphysema among Black men persist after further adjustment for age and smoking.”

The observational study focused on clinical and spirometry data from the CARDIA study in 2015-2016 and CT scans conducted in 2010-2011 among 2,674 participants. The primary outcome was emphysema prevalence among participants with various normal spirometry measures, including an FEV₁/FVC ratio of 0.7 or greater or at least the lower limit of normal and an FEV₁ between 80% and 99% or between 100% and 120% of predicted.

The cohort comprised 485 Black men, 762 Black women, 659 white men and 768 white women.

Among those with a race-specific FEV₁ between 80% and 99% of predicted, 6.5% had emphysema. In those with FEV₁ between 80% and 99% of predicted, compared with white men, emphysema prevalence was 3.9-fold higher among Black men and 1.9-fold higher among Black women compared with white women.

Among those with a race-specific FEV₁ between 100% and 120% of predicted, the prevalence of emphysema was 4%. Among these participants, emphysema prevalence was 6.4-fold higher among Black men compared with white men, but Black and white women had similar prevalence of 2.6% and 2%, respectively.

Researchers reported attenuation of racial differences in emphysema prevalence among men and elimination of racial differences among women with the use of race-neutral equations to identify those with an FEV₁ percent predicted between 80% and 120%.

“These findings magnify the need to reconsider the use of race-specific spirometry reference equations in favor of race-neutral equations,” the researchers wrote. “We conclude that visual emphysema should be included in definitions of ‘early COPD’ and CT imaging should be incorporated into the evaluation of those with suspected impaired respiratory health and normal spirometry findings.”