The impact of switching to race-neutral reference equations on FEV percent predicted among people with cystic fibrosis.

RATIONALE

The American Thoracic Society recommended switching to race-neutral spirometry reference equations, as race is a social construct and to avoid normalizing disparities in lung function due to structural racism. Understanding the impact of the race-neutral equations on percent predicted forced expiratory volume in one second (ppFEV) in people with cystic fibrosis (PwCF) will help prepare patients and providers to interpret pulmonary function test results.

OBJECTIVE(S): To quantify the impact of switching from Global Lung Initiative (GLI) 2012 race-specific to GLI 2022 Global race-neutral reference equations on the distribution of ppFEV among PwCF of different races.

METHODS

Cross-sectional analysis of FEV among PwCF ages ≥6 years in the 2021 U.S. Cystic Fibrosis Foundation Patient Registry. We describe the absolute difference in ppFEV between the two reference equations by reported race and the effect of age and height on this difference.

RESULTS

With the switch to GLI Global, ppFEV will increase for White (median increase 4.7, (IQR: 3.1; 6.4)) and Asian (2.6 (IQR: 1.6; 3.7)) individuals and decrease for Black individuals (-7.7, (IQR: -10.9; -5.2)). Other race categories will see minimal changes in median ppFEV. Individuals with higher baseline ppFEV and younger age will see a greater change in ppFEV (i.e., a greater improvement among White and Asian individuals and a greater decline among Black individuals).

CONCLUSIONS

Switching from GLI 2012 race-specific reference equations to GLI 2022 Global race-neutral equations will result in larger reductions in ppFEV among Black individuals with CF than increases among White and Asian people with CF.