Race-neutral versus race-specific GLI reference equations on spirometry interpretation in the general population.

Pulmonary function interpretation is key to the diagnosis and management of respiratory diseases. The Global Lung Function Initiative (GLI) introduced the race-specific reference equations for spirometry in 2012, with subsequent development of the race-neutral reference equations in 2022. This study examined the effects of transitioning from the race-specific 2012-GLI to the race-neutral 2022-GLI reference equations on spirometry interpretation in Northeast Asians. Spirometric data of 10,030 adults from the KoGES cohort were used to derive percent-predicted values using both GLI reference equations. The prevalence of lung function impairment and medical disability, associations of FEV and FVC percent-predicted with respiratory symptoms, and lung function trajectories were determined. Agreement between the two GLI reference equations for lung function impairment and medical disability classification were moderate to almost perfect. The use of the race-neutral 2022-GLI reference equations reclassified 48.9% and 39.9% of patients as having normal lung physiology or less severe medical disability. Associations between lower FEV₁ percent-predicted and worsening respiratory symptoms remained consistent across both reference equations. However, there was more rapid longitudinal decline in FEV (p < 0.001) and FVC (p < 0.001) using the race-neutral reference equations, compared to race-specific reference equations. The shift to race-neutral 2022 GLI reference equations reduces the prevalence of lung function impairment and medical disability classifications with different rates of lung function decline in Northeast Asians, despite consistent relationships with respiratory symptoms. Caution is needed when switching pulmonary function interpretation approaches, in particular the differential effects across race and ethnicity.