Implications of race-neutral equations on interpretation of lung function in Australia

In 2022, the American Thoracic and European Respiratory Societies recommended a shift to race-neutral equations for reporting and interpreting lung function tests. The impact of this change in the Australian population has not been comprehensively evaluated.

We conducted a cross-sectional study of adults evaluated at a multi-centre lung function laboratory in Australia between 2014 and 2024. Adults aged 40-70 years referred with respiratory symptoms or suspected obstructive airways disease were included (n = 6109). We compared the classification and severity of obstructive, restrictive, and mixed ventilatory defects using the race-neutral versus race-specific Global Lung Initiative reference equations.

Lung function tests from 6109 individuals with a mean (SD) age of 51.0 (13.7) years were evaluated (71% Caucasian, 9% South East (SE) Asian, 19% Other). Using race-neutral instead of race-specific equations resulted in 93% (5702 of 6109) remaining in the same classification. Among Caucasians, race-neutral equations increased the prevalence of obstruction (11%-13%), decreased restriction (8%-4%), and decreased mixed (4%-3%). Among SE Asians, race-neutral equations decreased the prevalence of obstruction (15%-10%) and increased restriction (6%-8%), and mixed was unchanged (2%). Among Others, race-neutral equations decreased the prevalence of obstruction (8%-7%), decreased restriction (21% to 17%) and decreased mixed (6% to 5%).

While race-neutral and race-specific equations had concordant classifications for most individuals, the change resulted in a relative decrease in the prevalence of restriction in Caucasians by 53% and obstruction in SE Asians by 35%.