Race/Ethnicity, Spirometry Reference Equations, and Prediction of Incident Clinical Events :The Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study

Rationale: Normal values for FEV₁ and FVC are currently calculated using cross-sectional reference equations that include terms for race/ethnicity, an approach that may reinforce disparities and is of unclear clinical benefit. Objectives: To determine whether race/ethnicity–based spirometry reference equations improve the prediction of incident chronic lower respiratory disease (CLRD) events and mortality compared with race/ethnicity–neutral equations. Methods: The MESA Lung Study, a population-based, prospective cohort study of White, Black, Hispanic, and Asian adults, performed standardized spirometry from 2004 to 2006. Predicted values for spirometry were calculated using race/ ethnicity–based equations following guidelines and, alternatively, race/ethnicity–neutral equations without terms for race/ethnicity. Participants were followed for events through 2019. Measurements and Main Results: The mean age of 3,344 participants was 65 years, and self-reported race/ethnicity was 36% White, 25% Black, 23% Hispanic, and 17% Asian. There were 181 incident CLRD-related events and 547 deaths over a median of 11.6 years. There was no evidence that percentage predicted FEV₁ or FVC calculated using race/ethnicity–based equations improved the prediction of CLRD-related events compared with those calculated using race/ethnicity–neutral equations (difference in C statistics for FEV₁, 20.005; 95% confidence interval [CI], 20.013 to 0.003; difference in C statistic for FVC, 20.008; 95% CI, 20.016 to 20.0006). Findings were similar for mortality (difference in C statistics for FEV₁, 20.002; 95% CI, 20.008 to 0.003; difference in C statistics for FVC, 20.004; 95% CI, 20.009 to 0.001). Conclusions: There was no evidence that race/ethnicity–based spirometry reference equations improved the prediction of clinical events compared with race/ethnicity–neutral equations. The inclusion of race/ethnicity in spirometry reference equations should be reconsidered.