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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.