Using race-based equations to evaluate lung disease -- a practice promoted in the 2019 guidelines of the American Thoracic Society -- may mean that severe lung disease in Black patients is classified as moderate disease, according to a UCSF-led study.
Race-based equations derive conceptually from the U.S. slavery era, when it was found that slaves had lower lung function relative to slaveholders. This was attributed to biology, rather than social and environmental factors, say the researchers in their study, published in the American Journal of Respiratory and Critical Care Medicine on Dec. 16, 2021.
“This is a concrete example of structural racism in health care,” said first author Aaron Baugh, MD, assistant professor in the UCSF Division of Pulmonary, Critical Care, Allergy and Sleep Medicine. “It is built into our system and delays lung transplants for Black patients, creating a higher standard for them to get disability for lung conditions, and biases doctors toward under-treatment.”
In the study the researchers compared data from SPIROMICS, a multi-center cohort of ever-smokers with or at risk of COPD (chronic obstructive pulmonary disease). They included 2,652 participants, of whom 530 identified as Black and 2,122 identified as White. When they applied the race-based formula using adjusted values for Black people in measuring the amount of air that can be forcefully exhaled in one second, they found that they had better lung function -- an average FEV1 score of 76.2 percent, versus 71.3 percent for White patients.
Using a universal formula for both Black and White participants, the average FEV1 score reached 77.4 percent for White patients, but dipped to 69.4 percent for Black patients, indicating more serious disease, depending on other factors like height and age.
Symptoms in Black Patients Negate Findings of Race-Based Equations
When researchers looked at other measures of disease, including patient-reported symptoms, airway wall thickness and results of a six-minute walk test, they found that the universal formula more accurately reflected disease severity than the race-based formula.
“Our research suggests that using separate lung function normalization equations for White and Black Americans is fundamentally flawed,” said co-senior author Prescott Woodruff, MD, professor and chief of the UCSF Division of Pulmonary, Critical Care, Allergy and Sleep Medicine and the Cardiovascular Research Institute. “The practice obscures real and clinically important decrements in lung function that Black Americans manifest, and which are likely related to structural racism and adverse social and environmental conditions.”
Researchers also pointed to the impact of environmental and social exposures. These conditions have long been known to be disproportionately negative for Black people, regardless of traditional markers of privilege like income or education. This study may be the first that documents how these effects of racial discrimination may negatively impact lung function, they noted.
The results of the study send a clear message to Black patients with undiagnosed or underdiagnosed lung disease, according to co-senior author Neeta Thakur, MD, associate professor in the UCSF School of Medicine: “What you are exposed to over your life has an impact on your lungs. Your symptoms should not be dismissed because your lung function is assessed as ‘normal,’” she said. “Our methods for interpretation are flawed, and we need to find better alternatives as well as be more patient-centered.”
Added first author Baugh: “We believe you. The system always should have been built to encourage doctors to take your symptoms seriously. We are sorry for all the ways it did not.”
For a full list of co-authors, please refer to the paper. The research was supported by several grants, including those from the National Heart, Lung and Blood Institute (U01HL137880, K24HL137013, K23HL125551,HL137013 and F32HL158160).
UCSF authors Aaron Baugh, MD, and Neeta Thakur, MD, have no conflicts of interest to disclose. Prescott Woodruff, MD, works as a consultant for numerous pharmaceutical companies.
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