Comparison of race-specific and race-neutral spirometry equations on the classification of restrictive lung physiology, interstitial lung disease, and lung transplant referral eligibility

Abstract

BackgroundRace-specific reference equations for spirometry including forced vital capacity (FVC) are under scrutiny in interstitial lung disease (ILD). Their influence on ILD and transplant decision-making warrants study. MethodsWe performed a retrospective cohort study of adults with FVC measurements at Duke University Medical Center between 1 October 2014 and 1 February 2023. Using Global Lung Initiative 2012 reference equations, we compared how race-specific and race-neutral equations classified FVC with potential restrictive physiology (z-score < -2). In the subgroup of patients diagnosed with ILD, we compared how race-specific and race-neutral equations classified FVC as warranting transplant referral (percent-predicted <80%). We compared overall rates, odds ratios (ORs) and 95% confidence intervals (CIs) using conditional logistic regression, and differences in timing. ResultsWe identified 45,587 patients including 550 with ILD. Race-specific equations classified potential restricted physiology 5.2% more White patients (23.8% versus 18.6%, OR 1.28, 95% CI 1.24-1.32), 14.3% fewer Black patients (24.1% versus 38.4%, OR 0.63, 95% CI 0.60-0.66), and 7.7% fewer Asian patients (14.8% versus 22.5%, OR 0.66, 95% CI 0.53-0.82) compared with race-neutral equations. In the ILD subgroup, race-specific equations classified 13.0% more White patients as warranting transplant referral consideration compared to race-neutral equations (57.8% versus 44.8%, OR 1.29, 95% CI 1.07-1.56). ConclusionRace-specific equations increased classification of potential restrictive physiology and transplant candidacy for White patients but decreased classification of potential restrictive physiology for Black and Asian patients. Race-specific equations in ILD and transplant decision-making warrant greater consideration given their potential to contribute to racial disparities.