Impact of Transitioning from Race-Specific to Race-Neutral GLI Equation on Lung Function in a Predominantly Caucasian Population

Introduction: Diagnosis and treatment decisions for many respiratory diseases are based on spirometric values. We compared the impact of changing the reference equations from GLI-2012 (race-specific) to GLI-2022 (race-neutral) in a predominantly Caucasian urban population. Methods: PneumoLaus is a sub-study of CoLaus|PsyCoLaus, an ongoing prospective observational study conducted in Lausanne, Switzerland. Participants performed spirometry at baseline (2014–2017) and at follow-up (2018–2021, FU). We analysed changes of %predicted values (PV) for forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) by comparing the GLI-2022 reference equation to GLI-2012. Sub-group analyses were performed for social class, sex, and age using paired t tests corrected by Holm-Bonferroni. We analysed the association of age, sex, and social class on the differences using linear regression. Results: A total of 3,330 participants were included at baseline and 2,005 at FU, >97% Caucasian. Employing GLI-2022 equations, the %PV and z score increased significantly for both FEV1 (4.2% PV and +0.31 z score at baseline, 4.6% PV and +0.28 z score at FU, both p < 0.0001) and FVC (4.9% PV and +0.34 z score at baseline, 5.6% PV and + 0.29 z score at FU, both p < 0.0001). Younger individuals, males, and participants with only compulsory school education experienced the greatest increase. The prevalence of low FEV1 and low FVC decreased using GLI-2022 references, while the prevalence of obstructive ventilatory impairment increased at baseline and FU (all p < 0.05). Conclusion: In this predominantly Caucasian urban population-based cohort, applying GLI-2022 equations led to a general FEV1 and FVC %PV increase, particularly among younger individuals, males, and participants with only compulsory school education. Applying GLI-2022 equations also led to a general FEV1 and FVC z score increase. These findings changes may carry relevant implications for clinical care and social policy decisions.