Rate of Respiratory Impairments in Black Patients Increases When PFTs Use Race-Neutral Reference Equations

Using race-neutral reference equations to determine pulmonary function test (PFT) results identified significantly more Black individuals with respiratory impairments compared with race and ethnicity-specific equations in a recent study. The findings, published in JAMA Network Open, suggest that racial bias may contribute to health disparities in respiratory care, according to the authors.

“We applied the race-neutral GLI [Global Lung Function Initiative] Global reference equations to a cohort of Black and White individuals and compared the resultant interpretations with those produced using the race-specific 2012 GLI reference equations,” the authors wrote. “Applying the race-neutral reference equations led to a significant increase both in the number of Black individuals with restrictive and nonspecific respiratory impairments and in the severity of these impairments.”

While race and ethnicity demographics are often used in pulmonary function testing to help interpret results, no biological reasoning or evidence confirms the need for such data to effectively interpret PFTs, according to the study authors. The aim of the analysis was to compare PFT interpretations using race-neutral equations developed by the GLI vs race and ethnicity-specific equations that were developed by the GLI in 2012.

Both the race-neutral and race and ethnicity-specific GLI reference equations were developed based on 74,187 individuals' spirometry data spanning 33 countries. All individuals whose data were used to develop the reference equations did not have a history of tobacco use or respiratory symptoms.

The cross-sectional study included 5709 White and 2722 Black patients who underwent PFTs between January 2010 and December 2020 at an academic medical center. All included patients had spirometry and lung volume measures available, and only initial PFTs for each patient were included in the analysis.

GLI race-specific questions included age, sex, standing height, and race as predictors of forced expiratory volume in the first second of expirations (FEV₁), forced vital capacity (FVC), and percent FVC exhaled in the first second (FEV₁/FVC). GLI race-neutral reference questions used the same set of patients, but only included age, sex, and standing height as predictors.

When race-neutral reference equations were used instead of race-specific reference equations for Black individuals, the prevalence of restriction increased from 26.8% (95% CI, 25.2%-28.5%) to 37.5% (95% CI, 35.7%-39.3%), and nonspecific pattern of impairment from 3.2% (95% CI, 2.5%-3.8%) to 6.5% (95% CI, 5.6%-7.4%). There was not a significant change in the prevalence of obstruction, which was 19.9% (95% CI, 18.4%-21.4%) using race-specific reference equations vs 19.5% (95% CI, 18.0%-21.0%) with race-neutral reference equations.

For White patients, using race-neutral reference equations led to a decrease in the prevalence of restriction from 22.6% (95% CI, 21.5%-23.6%) to 18% (95% CI, 17%-19%) and a decrease in prevalence of nonspecific patterns of impairment from 8.7% (95% CI, 7.9%-9.4%) to 4% (95% CI, 3.5%-4.5%). The prevalence of obstruction was similar regardless of the reference equation used (23.9% [95% CI, 22.8%-25.1%] vs 25.1% [95% CI, 23.9%-26.2%]).

Furthermore, race-neutral equations were associated with an increase in severity among 22.8% of Black individuals vs race and ethnicity-specific equations (95% CI, 21.2%-24.4%), as well as a decrease in severity in 19.3% of White patients (95% CI, 18.2%-20.3%) compared with race-specific reference equations.

The researchers acknowledge that the study had some limitations, such as only including data from a single center, only including White and Black individuals and no other self-reported ethnicities, and not including other clinical information when measuring FEV₁, FVC, and FEV₁/FVC z scores.

Despite these limitations, the researchers concluded that the study suggests racial and ethnic bias may be undermining the true prevalence and severity of respiratory illnesses among Black individuals undergoing PFTs compared with White individuals.

“The interpretive consequences that follow from the continued use of race-specific reference equations, coupled with the availability of the GLI Global reference equations, offer a strong argument in support of the routine use of these race-neutral reference equations for PFT interpretation,” wrote the researchers.

Reference

Moffett AT, Bowerman C, Stanojevic S, Eneanya ND, Halpern SD, Weissman GE. Global, Race-Neutral Reference Equations and Pulmonary Function Test Interpretation. JAMA Netw Open. 2023;6(6):e2316174. doi:10.1001/jamanetworkopen.2023.16174