Race-Specific Spirometry: No Benefit in CT or Dyspnea Models

Use of race-specific spirometry equations yielded no significant improvement in models of lung function involving dyspnea and quantitative chest CT according to data from two population-based cohorts.

Spirometry has traditionally included reference equations to estimate "normal" lung function that have included age, gender, height, and race/ethnicity, wrote Amy L. Non, PhD, of the University of California San Diego, La Jolla, and colleagues. Although the inclusion of race is based on population-wide studies showing lower measures of lung function for some racial and ethnic groups, the clinical value of the race element of these equations has been questioned, they said.

In a study published in the journal Chest, the researchers used data from the National Health and Nutrition Survey (NHANES) between 2007 and 2012 and the COPDGene study. The researchers used a population of 3700 healthy, never-smoking adults from the NHANES cohort and 419 from the COPDGene cohort to create equations that excluded race as well as equations that were race-specific. The NHANES cohort demographic were 38% White, 21% Black,18% Mexican-American,13% other Hispanic, and 10% mixed race or "other" races. The COPDGene cohort was 18% Black and 82% White.

The primary outcome was how effectively the percent predicted forced expiratory volume per 1 second (ppFEV₁) values on the basis of race-specific, race-neutral, and race-free reference equations explained dyspnea, chest abnormalities on CT, or Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification.

In comparing the models of never-smokers, the race-specific equations showed no advantage over the equations that included race. "Race-neutral equations generated higher predicted FEV₁ and [lower limit of normal] values than race-specific equations for the Black participants, but unchanged or minimally shifted to lower values in the White participants of both healthy, never-smoking cohorts," the researchers wrote.

Among smokers, the race-neutral equations perpetuated a shift in ppFEV₁ in the Black population to lower values and reclassified an average of 17.3% of Black smokers in the NHANES cohort into worse GOLD categories. 

"In the more severely diseased COPDGene cohort, 19% of Black participants were reclassified to worse GOLD classes using race-neutral/race-free equations," they said.

The findings were limited by several factors, including the cross-sectional design, relatively small Black population in the COPDGene cohort, and lack of representation of all racial and ethnic groups in the available data sets, the researchers noted. The current study also did not examine socioeconomic and environmental factors, which are important to explore in future studies, they said.

However, the results suggest that race-neutral or race-free reference equations may improve pulmonary disease diagnoses and therefore guide treatment more effectively than would race-specific equations in high-risk populations, the researchers concluded. 

The study was supported by the National Heart Lung, and Blood Institute. The COPDGene study also receives support from the COPD Foundation through contributions to an Industry Advisory Committee including AstraZeneca, Bayer Pharmaceuticals, Boehringer-Ingelheim, Genentech, GlaxoSmithKline, Novartis, Pfizer, and Sunovion. Non also disclosed support from a UCSD Academic Senate Grant and UCSD Division of Social Sciences Research Grant. 

Chest. Published online July 26, 2023. Full text

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