Race- and Ethnicity-Based Spirometry Reference Equations: Are They Accurate for Genetically Admixed Children?

Characterization of the phenotypic consequences of the Duffy-null genotype

ABSTRACT

A wealth of research focused on African American populations has connected rs2814778-CC ("Duffy-null") to decreased neutrophil (neutropenia) and leukocyte counts (leukopenia). Although it has been proposed that this variant is benign, prior studies have shown that the misinterpretation of Duffy-null-associated neutropenia and leukopenia can lead to unnecessary bone marrow biopsies, inequities in cytotoxic and chemotherapeutic treatment courses, underenrollment in clinical trials, and other disparities. To investigate the phenotypic correlates of Duffy-null status, we conducted a phenome-wide association study across >1400 clinical conditions in All of Us, the Vanderbilt University Medical Center's Biobank, and the Million Veteran Program. This reveals that Duffy-null status is only reproducibly associated with changes in white blood cell count and not with any disease outcomes. Moreover, we find that Duffy-null-associated neutropenia is on average less severe than other neutropenia cases in All of Us. We also show that this genotype is present in considerable frequencies in All of Us populations that are genetically similar to African (68%) and Middle Eastern (14%) 1000 Genomes/Human Genome Diversity Project reference populations as well as those who identify with >1 race (12%), as Pacific Islander (7%), and as Hispanic (5%). Furthermore, we find that race is not an accurate predictor of Duffy-null status or associated benign neutropenia. Our research suggests that broad genetic screening of rs2814778 across all populations could provide a more robust and accurate understanding of white blood cell count and mitigate resulting health disparities.

Perspectives on Using Race in Pulmonary Function Testing: A National Survey Fellows and Program Directors

BACKGROUND

Pulmonary function tests (PFTs) have historically used race-specific prediction equations. The recent American Thoracic Society guidelines recommend the use of a race-neutral approach in prediction equations. There are limited studies centering the opinions of practicing pulmonologists on the use of race in spirometry. Provider opinion will impact adoption of the new guideline. The aim of this study was to ascertain the beliefs of academic pulmonary and critical care providers regarding the use of race as a variable in spirometry prediction equations.

METHODS

We report data from 151 open-ended responses from a voluntary, nationwide survey (distributed by the Association of Pulmonary Critical Care Medicine Program Directors) of academic pulmonary and critical care providers regarding the use of race in PFT prediction equations. Responses were coded using inductive and deductive methods, and a thematic content analysis was conducted.

RESULTS

There was a balanced distribution of opinions among respondents supporting, opposing, or being unsure about the incorporation of race in spirometry prediction equations. Responses demonstrated a wide array of understanding related to the concept and definition of race and its relationship to physiology.

CONCLUSIONS

There was no consensus among providers regarding the use of race in spirometry prediction equations. Concepts of race having biologic implications persist among pulmonary providers and will likely affect the uptake of the Global Lung Function Initiative per the American Thoracic Society guidelines.

Comparison of race-specific and race-neutral GLI spirometric reference equations with an Indian reference equation

BACKGROUND

Despite the increasing popularity and use of Global Lung Function Initiative (GLI) spirometric reference equations, the appropriateness of the race-specific and race-neutral GLI spirometric reference models among the Indian population has not been systematically investigated.

METHODS

In this cross-sectional analysis, we used spirometric measurements of 1123 healthy Indian adults (≥18 years of age). We computed reference values and z-scores for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and FEV1/FVC from race-specific and race-neutral GLI reference equations as well as from a widely used Indian reference equation. We studied heterogeneity between GLI equations and the Indian equations using Bland-Altman analysis, and the differences between the reference and observed values were compared using the Friedman test.

RESULTS

In Bland-Altman analysis, significant heterogeneity in FVC and FEV1 between race-specific and Indian equations was observed (bias: 10.4 % and 14.1 %, respectively), with less bias for FEV1/FVC (3.76 %). The race-neutral equations showed almost similar bias (9.8 %, 13.8 %, and 3.8 % for FVC, FEV1, and FEV1/FVC, respectively). Median differences in race-specific reference values from observed values for FVC and FEV1 were 0.49L and 0.44L, respectively, decreasing slightly with race-neutral equations (0.46L and 0.43L) whereas Indian models showed minimal differences (FVC: 0.10L, FEV1: 0.05L). Z-scores for FVC and FEV1 were significantly different between race-specific and race-neutral GLI equations, and both differed from Indian equations.

CONCLUSION

Both race-specific and race-neutral GLI reference equations are significantly different from the Indian equations, which underscores the importance of determining the suitability of global reference models before being used indiscriminately.

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

Rationale: The use of self-reported race and ethnicity to interpret lung function measurements has historically assumed that the observed differences in lung function between racial and ethnic groups were because of thoracic cavity size differences relative to standing height. Very few studies have considered the influence of environmental and social determinants on pulmonary function. Consequently, the use of race and ethnicity-specific reference equations may further marginalize disadvantaged populations. Objectives: To develop a race-neutral reference equation for spirometry interpretation. Methods: National Health and Nutrition Examination Survey (NHANES) III data (n = 6,984) were reanalyzed with sitting height and the Cormic index to investigate whether body proportions were better predictors of lung function than race and ethnicity. Furthermore, the original GLI (Global Lung Function Initiative) data (n = 74,185) were reanalyzed with inverse-probability weights to create race-neutral GLI global (2022) equations. Measurements and Main Results: The inclusion of sitting height slightly improved the statistical precision of reference equations compared with using standing height alone but did not explain observed differences in spirometry between the NHANES III race and ethnic groups. GLI global (2022) equations, which do not require the selection of race and ethnicity, had a similar fit to the GLI 2012 "other" equations and wider limits of normal. Conclusions: The use of a single global spirometry equation reflects the wide range of lung function observed within and between populations. Given the inherent limitations of any reference equation, the use of GLI global equations to interpret spirometry requires careful consideration of an individual's symptoms and medical history when used to make clinical, employment, and insurance decisions.