Race-neutral lung function equations change spirometry interpretation in children
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Key takeaways:
- Black children had lower FEV1 and FVC percent predicted after race-neutral vs. -specific equation use.
- Black vs. white children were more likely to have spirometry pattern changes with the neutral equations.
Following use of race-neutral vs. -specific lung function equations, spirometry findings and patterns differed, especially among Black children/adolescents, according to results published in JAMA Pediatrics.
“Health care providers performing spirometry in children should know that implementing the race-neutral equations will have profound implications for test results,” Daniel J. Weiner, MD, FAAP, FCCP, ATSF, professor of pediatrics at the University of Pittsburgh and director of the Antonio J. and Janet Palumbo Cystic Fibrosis Center and pulmonary function and exercise laboratories at UPMC Children’s Hospital of Pittsburgh, told Healio.
“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,” he continued.
In a cross-sectional study, Weiner and colleagues assessed 24,630 individuals aged 6 to 21 years (mean age, 12.14 years; 53.67% male) with spirometry tests to observe how use of Global Lung Function Initiative (GLI) race-neutral reference equations vs. GLI-2012 race-specific equations change lung function measurements and patterns.
The total cohort included 19,503 white children/adolescents and 3,848 Black children/adolescents. The remaining 1,279 children/adolescents identified as a different race.
Lung function measurement changes
Researchers noted differences in the direction of FEV1 and FVC z scores with use of race-neutral vs. race-specific equations when split by race.
For Black children/adolescents, FEV1 z scores went down by 0.814 (95% CI, –0.823 to –0.806), FVC z scores went down by 0.911 (95% CI, –0.921 to –0.902) and FEV1/FVC z scores went up by 0.073 (95% CI, 0.069-0.076). When calculating the difference between race-neutral and race-specific equations, white children/adolescents had higher FEV1 z scores by 0.352 (95% CI, 0.349-0.355), higher FVC z scores by 0.35 (95% CI, 0.347-0.354) and lower FEV1/FVC z scores by 0.024 (95% CI, –0.025 to –0.023).
Additionally, Black children/adolescents had reduced FEV1 percent predicted (–10.74; 95% CI, –10.84 to –10.64), reduced FVC percent predicted (–11.98; 95% CI, –12.09 to –11.86) and elevated FEV1/FVC percent predicted (0.52; 95% CI, 0.51-0.53) after use of race-neutral vs. race-specific equations. White children continued to have the opposite direction of change from Black children/adolescents across all three measures (mean difference, FEV1 percent predicted, 4.12; 95% CI, 4.08-4.15; FVC percent predicted, 4.79; 95% CI, 4.74-4.83; FEV1/FVC percent predicted, –0.15; 95% CI, –0.15 to –0.14).
Spirometry pattern changes
Using z scores derived from each reference equation, researchers classified patterns on each child’s spirometry test as normal, obstructive, suspected restrictive, mixed, suspected dysanapsis or uncategorized.
The greatest proportion of children/adolescents with a different pattern following use of race-neutral vs. race-specific equations was observed among Black individuals (19.5%), followed by individuals of other races (8.4%) and white individuals (7.3%).
Use of race-neutral vs. race-specific equations resulted in fewer Black children/adolescents with a normal pattern (61.9% vs. 68.7%). Among those who no longer had a normal pattern, researchers found either suspected restrictive or uncategorized patterns.
Similar to the above finding, a lower proportion of Black children/adolescents had dysanapsis after the switch from race-specific to race-neutral equations, but a higher proportion of this cohort had obstructive, restrictive, mixed and uncategorized patterns.
In contrast, the cohort of white individuals with a normal pattern went up after use of race-neutral vs. race-specific equations (78.8% vs. 76.3%), as did the proportion of white individuals with a dysanapsis pattern. Fewer individuals in this cohort had an obstructive, restrictive, mixed and uncategorized pattern after the switch.
The adjusted likelihood for changes in the interpretation of spirometry patterns with the neutral equations was higher among Black vs. white children (aOR = 3.15; 95% CI, 2.86-3.48).
“We found pronounced differences by race in spirometry results when switching from race-specific to race-neutral equations,” Weiner told Healio. “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.”
Subgroup analysis
Lastly, researchers assessed spirometry pattern changes in a subgroup of children with asthma (n = 11,531).
As previously seen, Black children/adolescents with asthma had the largest proportion of pattern changes after use of race-neutral vs. race-specific equations (22.1%), followed by individuals of other races (10.2%) and white individuals (7.3%)
Use of race-neutral vs. race-specific equations resulted in fewer Black children/adolescents with asthma having a normal pattern (58.3% vs. 65.8%) and more white children/adolescents with asthma having a normal pattern (76.4% vs. 74.4%).
The adjusted odds for changes in the interpretation of spirometry patterns with the neutral equations were again greater among Black vs. white children with asthma (aOR = 3.56; 95% CI, 3.12-4.06).
“We expect that future studies that measure pulmonary function will use the race-neutral equations, and this means that we will expect different proportions of patients with obstructive or restrictive disorders than we have seen in the past,” Weiner said.
Importantly, Weiner added, “there may be some catch-up before all PFT software systems and PFT laboratories are using race-neutral equations.”