Omitting race from lung function equations increases detection of asthma in Black children, study shows

Despite ongoing progress, structural racism and health disparities continue to shape health care practices in ways health care providers may not even realize. A recent study in JAMA Network Open, published Feb. 28, 2025, shows that continued use of race-specific equations in the diagnostic process of children with asthma symptoms limits the identification of reduced lung function in Black children.

“This finding is important because when these children are not identified as having reduced lung function, they may not receive further testing. This can lead to under-diagnosis, delayed treatment, and long-term lung health issues,” says Gurjit Khurana Hershey, MD, Ph.D., senior author of the study.

Addressing an outdated equation

Diagnosing children with asthma is a multi-step process.

Reports of asthma symptoms from a physician or parental guardian start the diagnosis. Children then participate in pulmonary function testing to assess their lung function, including forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) tests. Children found to have abnormal lung function go on to further diagnostic testing.

Importantly, the FEV1 and FVC testing results in a percentage value compared to expected lung function. This expected lung function calculation is built into US spirometers–devices that measure lung function–and follows a standard equation using age, sex, body size and race.

Outdated and flawed studies led to the belief that white people have “naturally higher” lung function than other races. Thus, the calculation with race as a variable adjusts lung function by 10–15% for Black individuals and 4–6% for Asian individuals. However, this assumption and the resulting adjustments overlooks socioeconomic differences between racial groups. As a result, they unintentionally contribute to health disparities.

Updated equation still underused

In 2022, the Global Lung Initiative (GLI) Network updated lung function reference equations. To lower the negative impact of using race-specific equations, the new equations exclude race. However, health care providers have not universally adopted this new race-neutral equation.

The study led by first author Wan Chi Chang, MS, showed that the new race-neutral equation led to 2.5–4-fold more Black children with asthma symptoms as having reduced lung function compared to the race-specific equation.

This study included three cohorts of children from the Childhood Asthma Management Project (CAMP), the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS) and the Mechanisms of Progression of Atopic Dermatitis to Asthma (MPAACH) cohort. These cohorts include children with asthma or a high risk of asthma; 21% of these 1,533 children were Black. The use of the race-neutral equation changed 39% of all Black children from normal to reduced lung function when compared to the race-specific equation.

Additionally, when the race-neutral equation was used, 38–44% of Black children in the CCAAPS and MPAACH cohorts who were not initially eligible for further diagnostic testing became eligible. Importantly, using the race-neutral equation on white children had no meaningful impact on the lung function tests. These findings demonstrate that the race-specific equation overestimates lung function in Black children. This leads to the under-diagnosis of asthma in this group.

Co-authors of this study recommend the universal use of the race-neutral equation. This will increase the diagnosis and treatment of asthma and alleviate asthma-related health disparities. Moving forward, they propose further evaluations of the race-neutral equation in measuring lung function in other ethnic groups.