Kids’ Spirometry Results Differed When Switching to Race-Neutral Equations

Spirometry results in children were different after switching to race-neutral reference equations — with the potential to change how chronic lung diseases that are more prevalent in underrepresented minorities, like asthma, are treated.

Upon implementing race-neutral equations, there was a decrease in z scores among Black children for forced expiratory volume in 1 second (FEV1; mean difference −0.814, 95% CI −0.823 to −0.806, P<0.001) and forced vital capacity (FVC; −0.911, 95% CI −0.921 to −0.902, P<0.001), but FEV1/FVC z scores slightly increased (0.073, 95% CI 0.069-0.076, P<0.001), according to Christian Rosas-Salazar, MD, MPH, of Vanderbilt University Medical Center in Nashville, Tennessee, and colleagues.

In white children, z scores increased for FEV1 (mean difference 0.352, 95% CI 0.349-0.355, P<0.001) and FVC (mean difference 0.350, 95% CI 0.347-0.354, P<0.001), while there was a mild decrease in FEV1/FVC z scores (−0.024, 95% CI −0.025 to −0.023, P<0.001), they reported in JAMA Pediatrics. Similar changes were found when using percent predicted.

“This is an important study as race-neutral equations for spirometry were only recently developed and little is known about how implementing these equations could change lung function test results in children,” Rosas-Salazar told MedPage Today in an email.

The researchers noted that there has recently been “a strong movement to remove race from all normative equations used in the interpretation of pulmonary function tests.”

In models adjusted for a child’s age, sex, height, diagnosis, and study site, Black children had approximately 3-fold higher odds of changing spirometry pattern after the implementation of race-neutral equations (adjusted odds ratio [aOR] 3.15, 95% CI 2.86-3.48, P<0.001) compared with white children, while there was no difference noted for children of other races (aOR 1.20, 95% CI 0.97-1.47; P=0.09).

“In our study, we found pronounced differences by race in spirometry results when switching from race-specific to race-neutral equations,” Rosas-Salazar said. “While this was somewhat expected based on how these equations were derived, we did not anticipate the magnitude of these differences to be substantially larger in children of Black race.”

Overall, “[h]ealthcare providers performing spirometry in children should know that implementing the race-neutral equations will have profound implications for test results,” Rosas-Salazar continued. “Furthermore, they should know that while these new equations will impact results from children from all races, they are more likely to impact those from Black children.”

Rosas-Salazar and colleagues wrote that switching to race-neutral equations may re-classify most Black children as having a restrictive pattern in asthma rather than an uncategorized pattern, which would prompt additional testing. Similarly, it would reclassify most Black children with dysanapsis as having an obstructive pattern, leading to an escalation in asthma care or further testing, they added.

On the other hand, most white children with uncategorized asthma and a smaller proportion of those with a restrictive pattern will have a normal pattern, prompting consideration of decreasing or withdrawing asthma controller therapies, they noted.

Researchers performed a cross-sectional study of spirometry tests conducted in 24,630 children 6 to 21 years of age at two large academic pediatrics institutions in the U.S. between 2012 and 2022. Their study looked at differences in spirometry results and patterns after transitioning from Global Lung Function Initiative race-specific reference equations (GLIR, 2012) to Global Lung Function Initiative race-neutral reference equations (GLIN, 2023).

The children’s mean age was 12.1 years, and around 54% were male. Nearly 16% of participants were Black, 79.2% were white, and 5.2% were other races; 46.8% of participants had asthma, 2.1% had cystic fibrosis, and 51.1% had other diagnoses.

Limitations included that, because the research team used existing data from electronic health records, they were unable to assess spirometry technique. Also sample sizes for certain races (Northeast Asian, Southeast Asian, and other or mixed race) were small, and the research team lacked data on Hispanic ethnicity.

“Future, prospective studies in children should examine how a healthcare clinician’s clinical decision-making changes as a consequence of the adoption of GLIN and if the use of these equations influences the recognition, staging, and treatment of children with specific chronic lung diseases,” Rosas-Salazar and colleagues wrote.

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