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Updated: Sep 20, 2025
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Effects of Adoption of Race-Neutral Predictive Equations on Spirometry Results in Children With Sickle Cell Disease
Zena Ghazala1, Matthew Pertzborn1, Macey Feimster2
1Department of Pediatrics, Pediatric Pulmonary Division, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
Insights
New race-neutral spirometry equations lower lung function values in children with sickle cell disease (SCD), increasing the detection of lung impairment. This impacts monitoring of lung health in this vulnerable pediatric population.
Area of Science:
- Pediatric Pulmonology
- Hematology
- Medical Statistics
Background:
- Lung disease is a significant cause of illness and death in children with sickle cell disease (SCD).
- Spirometry is crucial for assessing lung function in children with SCD.
- Recent guidelines recommend race-neutral predictive equations for spirometry, replacing race-adjusted ones.
Purpose of the Study:
- To evaluate the impact of adopting race-neutral spirometry equations on lung function results in children with SCD.
- To assess how these changes affect the interpretation of lung health and impairment severity.
Main Methods:
- Retrospective analysis of spirometry data from 100 children (aged 5-21) with SCD.
- Calculated percent predicted (pp) and z-score values using both race-adjusted and race-neutral equations.
- Compared the prevalence of abnormal spirometry findings (FEV1, FVC, FEV1/FVC) and severity of impairment.
Main Results:
- Transitioning to race-neutral equations decreased mean ppFEV1 by 9.5% and ppFVC by 10.1%.
- Z-scores for FEV1 and FVC also decreased, indicating lower lung function.
- The adoption of race-neutral equations led to a threefold increase in identified cases of abnormal lung function and increased impairment severity.
Conclusions:
- Race-neutral spirometry reference equations result in lower FEV1 and FVC values (both z-scores and percent predicted) in children with SCD.
- These equations increase the detected severity of lung impairment in this population.
- Clinical interpretation of spirometry in pediatric SCD patients requires careful consideration of these new equations.
Background:
Lung disease is a major cause of morbidity and mortality in children with sickle cell disease (SCD), a condition that is more common in individuals of African American descent. Spirometry is utilized in monitoring lung health. Recently, the American Thoracic Society recommended the use of race-neutral predictive equations. We aimed to evaluate how the use of race-neutral equations may affect spirometry results and interpretation in children with SCD.
Methods:
This retrospective study included children aged 5-21 years with SCD followed at Arkansas Children's Hospital (01/01/2000-06/30/2023) who had completed at least one spirometry. Percent predictive (pp) and z-score values were calculated using race-adjusted and race-neutral predictive equations. Absolute and relative differences were calculated. Percent of subjects with forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) with z-score <-1.645 and pp < 80%, and FEV1/FVC z-score < -1.645 were compared. Severity of impairment based on z-score was compared.
Results:
One hundred children completed 460 spirometries. Transitioning from race-adjusted to race-neutral equations resulted in [mean (SD)]: a decrease in ppFEV1 [-9.497% (2.8344)], FEV1 z-score [-0.723 (0.2286)], ppFVC [-10.08% (3.3440)], FVC z-score [-0.750 (0.2757)], FEV1/FVC z-score [-0.057 (0.05461)], and an increase in ppFEV1/FVC [0.2785 (0.3921)]. Transitioning from race-adjusted to race-neutral equations resulted in an increase of impairment for FVC and FEV1 and a threefold increase in subjects with abnormal values.
Conclusions:
Adoption of race-neutral reference equations resulted in a decrease in FEV1 and FVC values (z-scores and percent predicted) and an increase in severity of impairment.
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