Black Men at Increased Risk of Misdiagnosis of Emphysema

Research presented at the American Thoracic Society 2022 International Conference¹ found that Black men were often determined to have normal lung function after race-based adjustments to spirometry before CT scans found emphysema.

Spirometry is a test of lung function in which a patient forcefully exhales into a mouthpiece connected to a spirometry machine. The machine measures the amount of air that the person is able to exhale and inhale, which is used to determine whether they have lung disease. Emphysema, a disease that involves the destruction of lung tissue, is associated with chronic obstructive pulmonary disease (COPD).²

The association between self-identified race and visually identified emphysema on CT scans in patients with normal spirometry were evaluated with the CARDIA study. Participants were separated by sex and by forced expiratory volume in 1 second (FEV₁) percent predicted and the lower limit of normal (LLN) for FEV₁ and FEV₁/forced vital capacity (FVC) ratio.

The cohort was also separated by sex-specific quartiles of FEV₁ volume divided by height in meters squared to remove race-based adjustment but still account for height as a biological factor that affects lung capacity.

There were 2674 participants in this study: 485 Black men, 762 Black women, 659 White men, and 768 White women. All participants had a CT scan at a mean age of 50 years and a spirometry at a mean age of 55 that were available for analysis.

Black men had a higher prevalence of emphysema compared with White men (15.5% vs 4.0%) and Black women had a higher prevalence of emphysema than White women (6.9% vs 3.2%) in participants with a FEV₁ between 80% and 99% predicted. Black men also had a higher prevalence of emphysema than White men (14.6% vs 1.7%) in participants with FEV₁ between 100% and 120% predicted; Black women and White women had similar rates of emphysema in this grouping (3.8% vs 1.9%).

Black men and women had a higher prevalence of emphysema than White men and women respectively when FEV₁/FVC ratio was greater than or equal to the LLN.

“Black adults in the United States are more likely to have unrecognized emphysema than White adults. This is due in part to the normalization of lower lung function in people of color through race-specific interpretations of spirometry,” said author Gabrielle Liu, MD, pulmonary and critical care fellow, Northwestern University Feinberg School of Medicine. “Our traditional measures of lung health based on race-specific spirometry may be considerably underrecognizing impaired respiratory health in Black individuals.”

The researchers concluded that use of measures from spirometry, like FEV₁/FVC ratio greater than or equal to LLN and FEV₁ greater than or equal to 80% predicted based on race-specific equations could result in misdiagnosis of lung disease in Black adults.

“This [research] suggests that the greatest potential for misclassification using race-specific equations occurs among Black adults who are at risk for disease and who could potentially benefit from risk factor modification,” said Liu.

References

1. Liu GY, Khan SS, Colangelo L, et al. Racial disparities in emphysema prevalence: the CARDIA lung study. Presented at: American Thoracic Society 2022 International Conference; May 13-18, 2022; San Francisco, CA. https://www.abstractsonline.com/pp8/#!/10476/presentation/4762
2. Many Black men with “normal” lung function may actually have emphysema. News release. American Thoracic Society. May 15, 2022. Accessed May 15, 2022. https://www.thoracic.org/about/newsroom/press-releases/conference/removal-of-race-correction-in-pulmonary-function-tests.php