Race-Neutral Spirometry Equations Catch Missed Lung Abnormalities in Black Adults

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Study shows the expected lung decline among those reclassified by the newer equations

by
Crystal Phend, Contributing Editor, MedPage Today
April 25, 2025 • 4 min read

Race-neutral equations for assessing lung function appeared to catch more true-abnormal findings for Black patients than did previously standard race-adjusted spirometry equations, a study showed.

In a large single center cohort, race-neutral Global Lung Function Initiative (GLI) reference equations reclassified forced expiratory volume in the first second of expiration (FEV₁) or forced vital capacity (FVC) from normal to abnormal for 19.2% of Black patients compared with the 2012 race-adjusted GLI reference equations, according to Darshali A. Vyas, MD, of Massachusetts General Hospital in Boston, and colleagues in JAMA Network Open.

Those reclassified cases appeared to have lung pathology missed by the prior equations, as the newly abnormal group had similar annual FEV₁ decline as Black patients with lung function deemed abnormal under both equations and numerically greater decline than seen in those classified as normal under both equations (-2.06%, -1.89%, and -1.59%, respectively).

“Taken together, the findings suggest that previous race-adjusted equations missed opportunities to detect true lung pathology earlier in Black patients,” noted Russell G. Buhr, MD, PhD, of the University of California Los Angeles David Geffen School of Medicine in an accompanying editorial. “The implications are substantial across various domains, from clinical medicine to research and public policy, and these findings further bolster the call to rethink how we distinguish between disease and normal in spirometry assessments.”

Indeed, the researchers agreed that “confidence in the appropriateness of these recategorizations is critical” as it carries “far-reaching consequences, from determining screening frequency and access to specialty care to identifying surgical candidacy, employment eligibility, and insurance coverage.”

Vyas and colleagues noted that there have been concerns that American Thoracic Society’s 2023 recommendation to switch to the race-neutral equations, dubbed GLI Global, might result in underdetection of lung disease in white patients.

However, that did not appear to be the case in the study.

For white patients, 15.0% had either their FEV₁ or FVC recategorized from abnormal under the race-adjusted equations to normal using the race-neutral equation. Their FEV₁ decline was similar to that of white patients deemed normal under both equations (-1.82% and -1.97% over the same time frame), “suggesting that white patients who change from an abnormal to normal spirometry interpretation are less likely to have lung pathology that is overlooked by the transition to race-neutral reference equation.”

The findings add to a growing body of evidence supporting the GLI Global reference equations for pulmonary function tests as being more accurate for Black populations of both adults and children, impacting potentially millions.

More nuanced but perhaps even more important for healthcare experts who routinely use spirometry, said Buhr, was the study’s data regarding changes in lung function over time.

“While some may question the validity of deriving and comparing slopes of change from unequal intervals with unbalanced repetitions, the approach is demonstrably sound, following data from the UPLIFT (Understanding Potential Long-Term Impacts on Function with Tiotropium) trial showing that linear models were as good as complex functions to track change in FEV₁ and that even as few as two measurements over 18 months can adequately determine FEV₁ change over time,” he wrote.

The cohort study included a total of 24,662 patients (4% Black, 53.2% women) ages 18 to 95 years (mean 57.6) who completed spirometry testing at Massachusetts General Hospital between Jan. 1, 1997, through Dec. 31, 2020. They completed a median 3.0 sets of spirometry over a median 2.6 years of follow-up.

The study didn’t show a similar trajectory for FVC as for FEV₁ among Black patients. Those recategorized from normal to abnormal had a trajectory similar to that of patients whose lung function remained normal regardless of the reference equation used, which the researchers called unexpected.

“Given that we lacked data on mortality, we were unable to account for the competing risk of death in this study population. It is likely that those with the worst lung function, as indicated by an abnormal FVC even in the setting of race-adjusted tools, would be at highest risk of mortality and other outcomes,” they wrote. “If there is differential loss to follow-up among the sickest patients in the population (those with the lowest FVC), then the FVC trajectory would be most preserved among that cohort of patients, as was the case in both the white and Black patients in this study.”

Another unexpected finding was that 22 white patients were recategorized from having normal to abnormal lung function with the use of the GLI Global reference equation, a predominantly male group which tended to be older. “These patients may simply be at the extremes of age, such that the stability of the equations is less reliable,” Vyas and colleagues said. “Alternatively, this population may represent an outlier within the GLI Global model that merits further exploration.”