Comparison of race-specific and race-neutral spirometry equations on the classification of restrictive lung physiology, interstitial lung disease, and lung transplant referral eligibility.
BACKGROUND: Race-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. METHODS: We performed a retrospective cohort study of adults with FVC measurements at Duke University Medical Center between October 1, 2014 and February 1, 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. RESULTS: We identified 45,587 patients, including 550 with ILD. Race-specific equations classified potential restricted physiology 5.2% more White patients (23.8% vs 18.6%, OR 1.28, 95% CI 1.24-1.32), 14.3% fewer Black patients (24.1% vs 38.4%, OR 0.63, 95% CI 0.60-0.66), and 7.7% fewer Asian patients (14.8% vs 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% vs 44.8%, OR 1.29, 95% CI 1.07-1.56). CONCLUSIONS: Race-specific equations increased the classification of potential restrictive physiology and transplant candidacy for White patients but decreased the 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.
