The purpose of our analysis was to study the clinical and occupational consequences from switching to a “race-neutral” spirometry reference equation for active-duty service members (ADSMs).

We hypothesized that switching to a “race-neutral” equation would affect eligibility for deployment and improve clinical accuracy. We tested this hypothesis using data from a prospective cohort study (STAMPEDE II) of ADSMs screened using spirometry pre-deployment. Prevalence of abnormality and z-scores were compared using the “race-neutral” GLI-Global (GLI-G) versus the original GLI 2012 (GLI-R) equations. The relationship between spirometry and deployment respiratory symptoms was modeled using ordinal logistic regression.

Among the 1632 subjects enrolled in STAMPEDE II, moving to GLI-G decreased z-scores and increased the prevalence of abnormality for Black ADSMs. For White and Hispanic ADSMs, z-scores increased and resulting abnormalities decreased. Among those referred for pre-deployment spirometry per current military protocols (n = 155), using GLI-G increased abnormal spirometry from 9.8 % to 11.6 % (p < 0.01), with a significant increase (5 (16.7 %) to 14 (46.7 %); p = 0.01) and decrease (6 (6.5 %) to 3 (3.2 %); p = 0.01) in abnormal spirometry in Black and White subjects, respectively. After adjustment for other factors, the presence of abnormal spirometry, whether defined by GLI-G or GLI-R, did not increase the odds for an increase in respiratory symptoms during or after deployment.

Among Black ADSMs, GLI-G decreases z-scores and results in an increase in abnormalities that will affect eligibility for deployment. Moving to a “race-neutral” equation did not improve clinical accuracy for predicting respiratory symptoms during or after deployment.