Race-neutral spirometry reclassification in self-identified Black and White patients

Recent consensus guidelines endorsed using a Global Lung Function Initiative (GLI Global) race-neutral approach to interpret spirometry. This study aims to examine how spirometry results using GLI Global reference equations correlate with patient healthcare utilisation and outcomes in a real-world cohort of patients.

Pulmonary function tests (PFTs) were analysed via race-specific and GLI Global approaches, respectively, using a 2010-2020 retrospective cohort study of spirometry tests. An abnormally low result for either forced vital capacity (FVC) or forced expiratory volume in 1 s (FEV₁) was defined as a z-score <-1.645. The 1-year pulmonary medication prescription, outpatient visit, emergency department (ED) visit or hospitalisation, as well as all-cause mortality were evaluated.

Out of the total cohort of 6107 tests, 530 (9%) and 595 (10%) results were re-classified when switching from race-specific to race-neutral for FEV₁ and FVC, respectively. Compared with patients whose lung function was consistently in the normal range (the control group), Black patients who were re-classified with an abnormally low FEV₁ had higher healthcare utilisation including pulmonary medication prescriptions, ED visits and worse outcomes such as hospitalisation. White individuals whose FEV₁ was re-classified as normal also had worse outcomes including higher mortality than the consistently normal group. Similar results were obtained when analysing FVC.

We conclude that both Black and White individuals whose FEV₁ and FVC were re-classified had worse outcomes compared with those who remained normal. Clinical context and judgment must be used when considering any lung function result near arbitrary thresholds of normal.