A Race-neutral Approach to the Interpretation of Lung Function Measurements

Early Evidence of Chronic Obstructive Pulmonary Disease Obscured by Race-Specific Prediction Equations

Rationale: The identification of early chronic obstructive pulmonary disease (COPD) is essential to appropriately counsel patients regarding smoking cessation, provide symptomatic treatment, and eventually develop disease-modifying treatments. Disease severity in COPD is defined using race-specific spirometry equations. These may disadvantage non-White individuals in diagnosis and care. Objectives: Determine the impact of race-specific equations on African American (AA) versus non-Hispanic White individuals. Methods: Cross-sectional analyses of the COPDGene (Genetic Epidemiology of Chronic Obstructive Pulmonary Disease) cohort were conducted, comparing non-Hispanic White (n = 6,766) and AA (n = 3,366) participants for COPD manifestations. Measurements and Main Results: Spirometric classifications using race-specific, multiethnic, and "race-reversed" prediction equations (NHANES [National Health and Nutrition Examination Survey] and Global Lung Function Initiative "Other" and "Global") were compared, as were respiratory symptoms, 6-minute-walk distance, computed tomography imaging, respiratory exacerbations, and St. George's Respiratory Questionnaire. Application of different prediction equations to the cohort resulted in different classifications by stage, with NHANES and Global Lung Function Initiative race-specific equations being minimally different, but race-reversed equations moving AA participants to more severe stages and especially between the Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 0 and preserved ratio impaired spirometry groups. Classification using the established NHANES race-specific equations demonstrated that for each of GOLD stages 1-4, AA participants were younger, had fewer pack-years and more current smoking, but had more exacerbations, shorter 6-minute-walk distance, greater dyspnea, and worse BODE (body mass index, airway obstruction, dyspnea, and exercise capacity) scores and St. George's Respiratory Questionnaire scores. Differences were greatest in GOLD stages 1 and 2. Race-reversed equations reclassified 774 AA participants (43%) from GOLD stage 0 to preserved ratio impaired spirometry. Conclusions: Race-specific equations underestimated disease severity among AA participants. These effects were particularly evident in early disease and may result in late detection of COPD.

ERS technical standard: Global Lung Function Initiative reference values for exhaled nitric oxide fraction (F ENO50 )

BACKGROUND

Elevated exhaled nitric oxide fraction at a flow rate of 50 mL·s-1 (F ENO50 ) is an important indicator of T-helper 2-driven airway inflammation and may aid clinicians in the diagnosis and monitoring of asthma. This study aimed to derive Global Lung Function Initiative reference equations and the upper limit of normal for F ENO50 .

METHODS

Available individual F ENO50 data were collated and harmonised using consensus-derived variables and definitions. Data collected from individuals who met the harmonised definition of "healthy" were analysed using the generalised additive models of location, scale and shape (GAMLSS) technique.

RESULTS

Data were retrospectively collated from 34 782 individuals from 34 sites in 15 countries, of whom 8022 met the definition of healthy (19 sites, 11 countries). Overall, height, age and sex only explained 12% of the between-subject variability of F ENO50 (R2=0.12). F ENO device was neccessary as a predictor of F ENO50 , such that the healthy range of values and the upper limit of normal varied depending on which device was used. The range of F ENO50 values observed in healthy individuals was also very wide, and the heterogeneity was partially explained by the device used. When analysing a subset of data in which F ENO50 was measured using the same device and a stricter definition of health (n=1027), between-site heterogeneity remained.

CONCLUSION

Available F ENO50 data collected from different sites using different protocols and devices were too variable to develop a single all-age reference equation. Further standardisation of F ENO devices and measurement are required before population reference values might be derived.

Application of Global Lung Function Initiative Global Spirometry Reference Equations across a Large, Multicenter Pulmonary Function Lab Population

Rationale: Global Lung Function Initiative (GLI) Global spirometry reference equations were recently derived to offer a "race-neutral" interpretation option. The impact of transitioning from the race-specific GLI-2012 to the GLI Global reference equations is unknown. Objectives: Describe the direction and magnitude of changes in predicted lung function measurements in a population of diverse race and ethnicity using GLI Global in place of GLI-2012 reference equations. Methods: In this multicenter cross-sectional study using a large pulmonary function laboratory database, 109,447 spirometry tests were reanalyzed using GLI Global reference equations and compared with the existing GLI-2012 standard, stratified by self-reported race and ethnicity. Measurements and Main Results: Mean FEV1 and FVC percent predicted increased in the White and Northeast Asian groups and decreased in the Black, Southeast Asian, and mixed/other race groups. The prevalence of obstruction increased by 9.7% in the White group, and prevalences of possible restriction increased by 51.1% and 37.1% in the Black and Southeast Asian groups, respectively. Using GLI Global in a population with equal representation of all five race and ethnicity groups altered the interpretation category for 10.2% of spirometry tests. Subjects who self-identified as Black were the only group with a relative increase in the frequency of abnormal spirometry test results (32.9%). Conclusions: The use of GLI Global reference equations will significantly impact spirometry interpretation. Although GLI Global offers an innovative approach to transition from race-specific reference equations, it is important to recognize the continued need to place these data within an appropriate clinical context.

Two is better than one: the double diffusion technique in classifying heart failure

Background

Heart failure (HF) is a chronic condition in which the heart does not pump enough blood to meet the body's demands. Diffusing capacity of the lung for nitric oxide (DLNO) and carbon monoxide (DLCO) may be used to classify patients with HF, as DLNO and DLCO are lung function measurements that reflect pulmonary gas exchange. Our objectives were to determine 1) if DLNO added to DLCO testing predicts HF better than DLCO alone and 2) whether the binary classification of HF is better when DLNO z-scores are combined with DLCO z-scores than using DLCO z-scores alone.

Methods

This was a retrospective secondary data analysis in 140 New York Heart Association Class II HF patients (ejection fraction <40%) and 50 patients without HF. z-scores for DLNO, DLCO and DLNO+DLCO were created from reference equations from three articles. The model with the lowest Bayesian Information Criterion was the best predictive model. Binary HF classification was evaluated with the Matthews Correlation Coefficient (MCC).

Results

The top two of 12 models were combined z-score models. The highest MCC (0.51) was from combined z-score models. At most, only 32% of the variance in the odds of having HF was explained by combined z-scores.

Conclusions

Combined z-scores explained 32% of the variation in the likelihood of an individual having HF, which was higher than models using DLNO or DLCO z-scores alone. Combined z-score models had a moderate ability to classify patients with HF. We recommend using the NO-CO double diffusion technique to assess gas exchange impairment in those suspected of HF.

Association of Preoperative Lung Function with Complications after Lobectomy Using Race-Neutral and Race-Specific Normative Equations

Rationale: Pulmonary function testing (PFT) is performed to aid patient selection before surgical resection for non-small cell lung cancer (NSCLC). The interpretation of PFT data relies on normative equations, which vary by race, but the relative strength of association of lung function using race-specific or race-neutral normative equations with postoperative pulmonary complications is unknown. Objectives: To compare the strength of association of lung function, using race-neutral or race-specific equations, with surgical complications after lobectomy for NSCLC. Methods: We studied 3,311 patients who underwent lobectomy for NSCLC and underwent preoperative PFT from 2001 to 2021. We used Global Lung Function Initiative equations to generate race-specific and race-neutral normative equations to calculate percentage predicted forced expiratory volume in 1 second (FEV1%). The primary outcome of interest was the occurrence of postoperative pulmonary complications within 30 days of surgery. We used unadjusted and race-adjusted logistic regression models and least absolute shrinkage and selection operator analyses adjusted for relevant comorbidities to measure the association of race-specific and race-neutral FEV1% with pulmonary complications. Results: Thirty-one percent of patients who underwent surgery experienced pulmonary complications. Higher FEV1, whether measured with race-neutral (odds ratio [OR], 0.98 per 1% change in FEV1% [95% confidence interval (CI), 0.98-0.99]; P < 0.001) or race-specific (OR, 0.98 per 1% change in FEV1% [95% CI, 0.98-0.98]; P < 0.001) normative equations, was associated with fewer postoperative pulmonary complications. The area under the receiver operator curve for pulmonary complications was similar for race-adjusted race-neutral (0.60) and race-specific (0.60) models. Using least absolute shrinkage and selection operator regression, higher FEV1% was similarly associated with a lower rate of pulmonary complications in race-neutral (OR, 0.99 per 1% [95% CI, 0.98-0.99]) and race-specific (OR, 0.99 per 1%; 95% CI, 0.98-0.99) models. The marginal effect of race on pulmonary complications was attenuated in all race-specific models compared with all race-neutral models. Conclusions: The choice of race-specific or race-neutral normative PFT equations does not meaningfully affect the association of lung function with pulmonary complications after lobectomy for NSCLC, but the use of race-neutral equations unmasks additional effects of self-identified race on pulmonary complications.

Short airway telomeres are associated with primary graft dysfunction and chronic lung allograft dysfunction

Primary graft dysfunction (PGD) is a major risk factor for chronic lung allograft dysfunction (CLAD) following lung transplantation, but the mechanisms linking these pathologies are poorly understood. We hypothesized that the replicative stress induced by PGD would lead to erosion of telomeres, and that this telomere dysfunction could potentiate CLAD. In a longitudinal cohort of 72 lung transplant recipients with >6 years median follow-up time, we assessed tissue telomere length, PGD grade, and freedom from CLAD. Epithelial telomere length and fibrosis-associated gene expression were assessed on endobronchial biopsies taken at 2 to 4 weeks post-transplant by TeloFISH assay and nanoString digital RNA counting. Negative-binomial mixed-effects and Cox-proportional hazards models accounted for TeloFISH staining batch effects and subject characteristics including donor age. Increasing grade of PGD severity was associated with shorter airway epithelial telomere lengths (p = 0.01). Transcriptomic analysis of fibrosis-associated genes showed alteration in fibrotic pathways in airway tissue recovering from PGD, while telomere dysfunction was associated with inflammation and impaired remodeling. Shorter tissue telomere length was in turn associated with increased CLAD risk, with a hazard ratio of 1.89 (95% CI 1.16-3.06) per standard deviation decrease in airway telomere length, after adjusting for subject characteristics. PGD may accelerate telomere dysfunction, potentiating immune responses and dysregulated repair. Epithelial cell telomere dysfunction may represent one of several mechanisms linking PGD to CLAD.

Race-Specific Spirometry Equations Do Not Improve Models of Dyspnea and Quantitative Chest CT Phenotypes

BACKGROUND

Race-specific spirometry reference equations are used globally to interpret lung function for clinical, research, and occupational purposes, but inclusion of race is under scrutiny.

RESEARCH QUESTION

Does including self-identified race in spirometry reference equation formation improve the ability of predicted FEV1 values to explain quantitative chest CT abnormalities, dyspnea, or Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification?

STUDY DESIGN AND METHODS

Using data from healthy adults who have never smoked in both the National Health and Nutrition Survey (2007-2012) and COPDGene study cohorts, race-neutral, race-free, and race-specific prediction equations were generated for FEV1. Using sensitivity/specificity, multivariable logistic regression, and random forest models, these equations were applied in a cross-sectional analysis to populations of individuals who currently smoke and individuals who formerly smoked to determine how they affected GOLD classification and the fit of models predicting quantitative chest CT phenotypes or dyspnea.

RESULTS

Race-specific equations showed no advantage relative to race-neutral or race-free equations in models of quantitative chest CT phenotypes or dyspnea. Race-neutral reference equations reclassified up to 19% of Black participants into more severe GOLD classes, while race-neutral/race-free equations may improve model fit for dyspnea symptoms relative to race-specific equations.

INTERPRETATION

Race-specific equations offered no advantage over race-neutral/race-free equations in three distinct explanatory models of dyspnea and chest CT scan abnormalities. Race-neutral/race-free reference equations may improve pulmonary disease diagnoses and treatment in populations highly vulnerable to lung disease.

Applicability of the Global Lung Function Initiative prediction equations in Hong Kong Chinese children

BACKGROUND AND OBJECTIVE

This study aimed to assess the applicability of the Global Lung Function Initiative (GLI) prediction equations for spirometry in Hong Kong children and to develop prediction equations based on the Generalized Additive Models for Location, Scale, and Shape (GAMLSS) modeling.

METHODS

Healthy Chinese children and adolescents aged 6-17 years old were recruited from randomly selected schools to undergo spirometry. The measurements were transformed to z-score according to the GLI-2012 equations for South East (SE) Asians and the GLI-2022 global race-neutral equations. Prediction equations for spirometric indices were developed with GAMLSS modeling to identify predictors.

RESULTS

A total of 886 children (477 boys) with a mean age of 12.5 years (standard deviation [SD] 3.3 years) were included. By the GLI-2012 SE Asian equations, positive mean z-scores were observed in forced expiratory volume in 1 s (FEV1 ) (boys: 0.138 ± SD 0.828; girls: 0.206 ± 0.823) and forced vital capacity (FVC) (boys: 0.160 ± 0.930; girls: 0.310 ± 0.895) in both sexes. Negative mean z-scores were observed in FEV1 /FVC ratio (boys: -0.018 ± 0.998; girls: -0.223 ± 0.897). In contrast, negative mean z-scores in FEV1 and FVC, and positive mean z-scores in FEV1 /FVC were observed when adopting the GLI-2022 race-neutral equations. The mean z-scores were all within the range of ±0.5. By GAMLSS models, age and height were significant predictors for all four spirometric indices, while weight was an additional predictor for FVC and FEV1 .

CONCLUSION

Our study provided data supporting the applicability of the GLI prediction equations in Hong Kong Chinese children. The GLI-2012 equations may underestimate FEV1 and FVC, while the GLI-2022 equations may overestimate the parameters, but the differences lie within the physiological limits. By GAMLSS modeling, weight was an additional predictor for FVC and FEV1 .

Bronchodilator response does not associate with asthma control or symptom burden among patients with poorly controlled asthma

PURPOSE

The purpose of this study was to determine how four different definitions of bronchodilator response (BDR) relate to asthma control and asthma symptom burden in a large population of participants with poorly controlled asthma.

PROCEDURES

We examined the baseline change in FEV1 and FVC in response to albuterol among 931 participants with poorly controlled asthma pooled from three clinical trials conducted by the American Lung Association - Airways Clinical Research Centers. We defined BDR based on four definitions and analyzed the association of each with asthma control as measured by the Asthma Control Test or Asthma Control Questionnaire, and asthma symptom burden as measured by the Asthma Symptom Utility Index.

MAIN FINDINGS

A BDR was seen in 31-42% of all participants, depending on the definition used. There was good agreement among responses (kappa coefficient 0.73 to 0.87), but only 56% of participants met all four definitions for BDR. A BDR was more common in men than women, in Blacks compared to Whites, in non-smokers compared to smokers, and in non-obese compared to obese participants. Among those with poorly controlled asthma, 35% had a BDR compared to 25% of those with well controlled asthma, and among those with a high symptom burden, 34% had a BDR compared to 28% of those with a low symptom burden. After adjusting for age, sex, height, race, obesity and baseline lung function, none of the four definitions was associated with asthma control or symptom burden.

CONCLUSION

A BDR is not associated with asthma control or symptoms in people with poorly controlled asthma, regardless of the definition of BDR used. These findings question the clinical utility of a BDR in assessing asthma control and symptoms.

Race as a Component of Cardiovascular Disease Risk Prediction Algorithms

PURPOSE OF REVIEW

Several prediction algorithms include race as a component to account for race-associated variations in disease frequencies. This practice has been questioned recently because of the risk of perpetuating race as a biological construct and diverting attention away from the social determinants of health (SDoH) for which race might be a proxy. We evaluated the appropriateness of including race in cardiovascular disease (CVD) prediction algorithms, notably the pooled cohort equations (PCE).

RECENT FINDINGS

In a recent investigation, we reported substantial and biologically implausible differences in absolute CVD risk estimates upon using PCE for predicting CVD risk in Black and White persons with identical risk factor profiles, which might result in differential treatment decisions based solely on their race. We recommend the development of raceless CVD risk prediction algorithms that obviate race-associated risk misestimation and racializing treatment practices, and instead incorporate measures of SDoH that mediate race-associated risk differences.

Impact of Spirometry Race-Correction on Preadolescent Black and White Children

BACKGROUND

Race-correction for Black patients is standard practice in spirometry testing. History suggests that these corrections are at least partially a result of racist assumptions regarding lung anatomy among Black individuals, which can potentially lead to less frequent diagnoses of pulmonary diseases in this population.

OBJECTIVE

To evaluate the impact of race-correction in spirometry testing among Black and White preadolescents, and examine the frequency of current asthma symptoms in Black children who were differentially classified depending on whether race-corrected or race-uncorrected reference equations were deployed.

METHODS

Data from Black and White children who completed a clinical examination at age 10 years from a Detroit-based unselected birth cohort were analyzed. Global Lung Initiative 2012 reference equations were applied to spirometry data using both race-corrected and race-uncorrected (ie, population-average) equations. Abnormal results were defined as values less than the fifth percentile. Asthma symptoms were assessed concurrently using the International Study of Asthma and Allergies in Childhood questionnaire, while asthma control was assessed using the Asthma Control Test.

RESULTS

The impact of race-correction on forced expiratory volume in 1 second (FEV1)/forced vital capacity ratio was minimal, but abnormal classification of FEV1 results more than doubled among Black children when race-uncorrected equations were used (7% vs 18.1%) and were almost 8 times greater based on forced vital capacity classification (1.5% vs 11.4%). More than half of Black children differentially classified on FEV1 (whose FEV1 was classified as normal with race-corrected equations but abnormal with race-uncorrected equations) experienced asthma symptoms in the past 12 months (52.6%), which was significantly higher than the percentage of Black children consistently classified as normal (35.5%, P = .049), but similar to that of Black children consistently classified as abnormal using both race-corrected and race-uncorrected equations (62.5%, P = .60). Asthma Control Test scores were not different based on classification.

CONCLUSIONS

Race-correction had an extensive impact on spirometry classification in Black children, and differentially classified children had a higher rate of asthma symptoms than children consistently classified as normal. Spirometry reference equations should be reevaluated to be aligned with current scientific perspectives on the use of race in medicine.

Towards a Race-Neutral System of Pulmonary Function Test Results Interpretation

It has been observed widely that, on average, Black individuals in the United States have lower FVC than White individuals, which is thought to reflect a combination of genetic, environmental, and socioeconomic factors that are difficult to disentangle. Debate therefore persists even after the American Thoracic Society's 2023 guidelines recommending race-neutral pulmonary function test (PFT) result interpretation strategies. Advocates of race-based PFT results interpretation argue that it allows for more precise measurement and will minimize disease misclassification. In contrast, recent studies have shown that low lung function in Black patients has clinical consequences. Furthermore, the use of race-based algorithms in medicine in general is increasingly being questioned for its risk of perpetuating structural health care disparities. Given these concerns, we believe it is time to adopt a race-neutral approach, but note that more research is urgently needed to understand how race-neutral approaches impact PFT results interpretation, clinical decision-making, and patient outcomes. In this brief case-based discussion, we offer a few examples of how a race-neutral PFT results interpretation strategy will impact individuals from racial and ethnic minority groups at different scenarios and stages of life.

Race-neutral equations for assessment of lung function in children with thalassemia

The aim of this study was to assess pulmonary dysfunction in children with transfusion-dependent thalassemia (TDT) using the Global Lung Function Initiative (GLI) 2022 race-neutral spirometric reference equations and to determine the main predicting factors. The spirometric results of 68 children with TDT were compared to the results of 68 healthy control subjects using both GLI-2012 reference equations for Caucasians and GLI-2022 global equations. Associations between the spirometric data and various anthropometric, clinical, and laboratory parameters were analyzed to detect predictors of pulmonary dysfunction in this group of patients. Children with TDT showed significantly lower values of FVC and FEV1 with a predominance of the restrictive pattern (23.53%). Thalassemic children with the restrictive pattern were significantly older, had a longer duration of regular blood transfusion, lower height, weight, and BMI z-scores, higher average serum ferritin, and higher frequency of having a serum ferritin level >2500 ng/mL. The strongest predictor for having a restrictive spirometric pattern was high serum ferritin. Our analysis shows that the transition from GLI-2012 spirometric reference equations for Caucasians to the GLI-2022 global equations has led to a reduction in the prevalence rate of restrictive pulmonary dysfunction in children with TDT, which should not affect the patient outcome in the long term. Asymptomatic children with TDT exhibited a restrictive spirometric pattern in a significant proportion. The most important predictor was high serum ferritin. We encourage the inclusion of pulmonary function testing in the routine monitoring of patients with TDT, especially in older patients and those with iron overload.

Race-specific spirometry equations may overestimate asthma control in Black children and adolescents

BACKGROUND

A growing body of evidence suggests that use of race terms in spirometry reference equations underestimates disease burden in Black populations, which may lead to disparities in pulmonary disease outcomes. Data on asthma-specific health consequences of using race-adjusted spirometry are lacking.

METHODS

We performed a secondary analysis of 163 children from two observational asthma studies to determine the frequencies of participants with ppFEV1 < 80% (consistent with uncontrolled asthma) or ppFEV1 ≥ 80% using race-specific (GLI-African American or Caucasian) vs. race-neutral (GLI-Global) spirometry and their alignment with indicators of asthma control (Asthma Control Test™, ACT). Comparisons of mean ppFEV1 values were conducted using Wilcoxon matched-pairs signed-rank tests. Two group comparisons were conducted using Wilcoxon rank-sum tests.

RESULTS

Data from 163 children (100 Black, 63 White) were analyzed. Mean ppFEV1 was 95.4% (SD 15.8) using race-specific spirometry and 90.4% (16.3) using race-neutral spirometry (p < 0.0001). Among 54 Black children with uncontrolled asthma (ACT ≤ 19), 20% had ppFEV1 < 80% using race-specific spirometry compared to 40% using race-neutral spirometry. In Black children with controlled asthma (ACT > 19), 87% had ppFEV1 ≥ 80% using race-specific compared to 67% using race-neutral spirometry. Children whose ppFEV1 changed to ≤ 80% with race-neutral spirometry had lower FEV1/FVC compared to those whose ppFEV1 remained ≥ 80% [0.83 (0.07) vs. 0.77 (0.05), respectively; p = 0.04], suggesting greater airway obstruction. Minimal changes in alignment of ppFEV1 with ACT score were observed for White children.

CONCLUSIONS

Use of race-specific reference equations in Black children may increase the risk of inappropriately labeling asthma as controlled.

Effect of Race and Ethnicity on Pulmonary Function Testing Interpretation: An American College of Chest Physicians (CHEST), American Association for Respiratory Care (AARC), American Thoracic Society (ATS), and Canadian Thoracic Society (CTS) Evidence Review and Research Statement

BACKGROUND

Calls have been made to discontinue the routine use of race and ethnicity in medicine. Specific to respiratory medicine, the use of race- and ethnicity-specific reference equations for the interpretation of pulmonary function test (PFT) results has been questioned.

RESEARCH QUESTIONS

Three key questions were addressed: (1) What is the current evidence supporting the use of race- and ethnicity-specific reference equations for the interpretation of PFTs? (2) What are the potential clinical implications of the use or nonuse of race and ethnicity in interpreting PFT results? and (3) What research gaps and questions must be addressed and answered to understand better the effect of race and ethnicity on PFT results interpretation and potential clinical and occupational health implications?

STUDY DESIGN AND METHODS

A joint multisociety (American College of Chest Physicians, American Association for Respiratory Care, American Thoracic Society, and Canadian Thoracic Society) expert panel was formed to undertake a comprehensive evidence review and to develop a statement with recommendations to address the research questions.

RESULTS

Several assumptions and gaps, both in the published literature and in our evolving understanding of lung health, were identified. It seems that many past perceptions and practices regarding the effect of race and ethnicity on PFT results interpretation are based on limited scientific evidence and measures that lack reliability.

INTERPRETATION

A need exists for more and better research that will inform our field about these many uncertainties and will serve as a foundation for future recommendations in this area. The identified shortcomings should not be discounted or dismissed because they may enable flawed conclusions, unintended consequences, or both. Addressing the identified research gaps and needs would allow a better-a more informed-understanding of the effects of race and ethnicity on PFT results interpretation.

Global, Race-Neutral Reference Equations and Pulmonary Function Test Interpretation

Importance

Race and ethnicity are routinely used to inform pulmonary function test (PFT) interpretation. However, there is no biological justification for such use, and it may reinforce health disparities.

Objective

To compare the PFT interpretations produced with race-neutral and race-specific equations.

Design, Setting, and Participants

In this cross-sectional study, race-neutral reference equations recently developed by the Global Lung Function Initiative (GLI) were used to interpret PFTs performed at an academic medical center between January 2010 and December 2020. The interpretations produced with these race-neutral reference equations were compared with those produced using the race and ethnicity-specific reference equations produced by GLI in 2012. The analysis was conducted from April to October 2022.

Main Outcomes and Measures

The primary outcomes were differences in the percentage of obstructive, restrictive, mixed, and nonspecific lung function impairments identified using the 2 sets of reference equations. Secondary outcomes were differences in severity of these impairments.

Results

PFTs were interpreted from 2722 Black (686 men [25.4%]; mean [SD] age, 51.8 [13.9] years) and 5709 White (2654 men [46.5%]; mean [SD] age, 56.4 [14.3] years) individuals. Among Black individuals, replacing the race-specific reference equations with the race-neutral reference equations was associated with an increase in the prevalence of restriction from 26.8% (95% CI, 25.2%-28.5%) to 37.5% (95% CI, 35.7%-39.3%) and of a nonspecific pattern of impairment from 3.2% (95% CI, 2.5%- 3.8%) to 6.5% (95% CI, 5.6%-7.4%) and no significant change in the prevalence of obstruction (19.9% [95% CI, 18.4%-21.4%] vs 19.5% [95% CI, 18.0%-21.0%]). Among White individuals, replacing the race-specific reference equations with the race-neutral reference equations was associated with a decrease in the prevalence of restriction from 22.6% (95% CI, 21.5%-23.6%) to 18.0% (95% CI, 17.0%-19.0%), a decrease in the prevalence of a nonspecific pattern of impairment from 8.7% (95% CI, 7.9%-9.4%) to 4.0% (95% CI, 3.5%-4.5%), and no significant change in the percentage with obstruction from 23.9% (95% CI, 22.8%-25.1%) to 25.1% (95% CI, 23.9%- 26.2%). The race-neutral reference equations were associated with an increase in severity in 22.8% (95% CI, 21.2%-24.4%) of Black individuals and a decrease in severity in 19.3% (95% CI, 18.2%-20.3%) of White individuals vs the race-specific reference equations.

Conclusions and Relevance

In this cross-sectional study, the use of race-neutral reference equations to interpret PFTs resulted in a significant increase in the number of Black individuals with respiratory impairments along with a significant increase in the severity of the identified impairments. More work is needed to quantify the effect these reference equations would have on diagnosis, referral, and treatment patterns.