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SURGICAL PERSPECTIVES

The End of Race Correction in Spirometry for Pulmonary Function Testing and Surgical Implications

Bonner, Sidra N. MD, MPH∗,†,‡; Wakeam, Elliot MD, MPH†,§

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doi: 10.1097/SLA.0000000000005431
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On October 14, 2021, the United States House of Representatives Ways and Means Committee released a final report to end the misuse of race in clinical decision support tools, including pulmonary function testing with spirometry.1 The decision of the Committee to address the historical practice of “race correction,” a process of adjusting clinical values and algorithms according to racial groups, is the summation of decades worth of scholarship and advocacy to address the origins of race correction and its amplification of racial disparities.2 Currently, over 120,000 operations are performed annually for benign and malignant pulmonary conditions for which pulmonary function testing with spirometry is a fundamental component of pre-operative evaluation.3 In this viewpoint, we outline the history of race correction in the assessment of lung function with spirometry in the United States, the implications for patients undergoing thoracic surgical evaluation and future responsibilities of the surgical community.

HISTORICAL CONTEXT FOR RACE-CORRECTION AND SPIROMETRY

The concept of racial differences in lung function in the United States was first conceived during slavery as a tool to reinforce the ideology of biologic differences between racial groups.4 The most cited first documentation of the concept of racial differences in lung function occurred in Notes on the State of Virginia published in 1787 by Thomas Jefferson. In this, Jefferson wrote extensively of the “difference of structure in the pulmonary apparatus” with reference to a deficiency in the respiratory cycle between Black enslaved people compared to White people.4 Although Jefferson's writings lacked empiric investigation, racial differences in lung function would become a major focus of medical research soon after his writing to justify the system of slavery.4,5 Nearly a century later, Samuel Cartwright, a physician and slave owner, was the first to report differences between Black enslaved people and White people using spirometry. His published writings reported a 20% deficiency in the pulmonary capacity of Black enslaved people, spawning the idea that forced labor improved the pulmonary function of enslaved individuals and building the foundation of what would become the normalization of race-correction in pulmonary tests.4,5

THE LIMITATIONS OF CURRENT RESEARCH AND RACE-CORRECTED EQUATIONS USED

Decade's worth of research using race as a proxy for genetic differences and lack of inclusion of known risk factors for poor lung function have resulted in innumerable “race-corrected” reference equations in spirometry. In 1999, the National Health and Nutrition Examination Survey created race and ethnicity specific spirometry standards for African American, White, and Mexican Americans and a race correction for Asian-Americans.6 In 2012, the Global Lung Function Initiative endorsed by six professional societies across the globe provided race-corrected equations for White, African Americans, Northeast Asians, Southeast Asian, and Other/Mixed. Notably for these equations, no data from Black populations outside of the United States were used and all individuals, who do not self-identify within the four racial groups are recommended to use the “other/Mixed” category.7,8 A prior systematic review of articles between 1922 and 2008 comparing “White” to “Other racial and ethnic groups” demonstrated that 94% of articles failed to include measures of socioeconomic status in analyses and that 29% explained differences in spirometry values as being the result of innate differences between races.9 Furthermore, factors such as smoking status, childhood respiratory illness, obesity, and environmental exposures to air pollution, known contributors to lung function, are not included in interpretation of results.7,8 Additional arguments against the inclusion of race-corrected equations include the variation of how race is reported by an individual or determined by the provider, the lack of inclusion of multi-racial categories in equations, and the wide variation in spirometry values within racial groups.7 Recent studies have demonstrated that race-correction in spirometry can lead to misdiagnosis or misclassification of medical diagnoses including asthma and chronic obstructive pulmonary dysfunction for patients.10,11 Lastly, and importantly, the persistent use of race, a socio-political construct based on the physical appearance of an individual, as a proxy for genetic difference in lung function is wrong. It relies on long-disputed theories of biological race which attributes differences between racial groups to a disproven hierarchy biologic function and fails to capture unmeasured risk factors and exposures, including individual and structural racism.12 The reliance on these equations means that surgical decision making is currently be unduly influenced by incorrect information.

RACE-CORRECTED PULMONARY FUNCTION TEST AND SURGICAL CARE

Spirometry is a core pulmonary function test used to evaluate surgical candidacy for benign and malignant lung resections, lung transplantation, and other thoracic operations such as esophagectomy. Forced expiratory volume in one second (FEV1) reported in spirometry testing has particularly significant importance. Specific cut-off values of FEV1 for the remnant pulmonary function used to determine quality of life after resection, preoperative risk by calculating “predicted postoperative FEV1,” and additional preoperative testing. Currently, patients are supposed to self-identify their race before spirometry testing and the racial group provided is used in “race-corrected” predicted FEV1 values. This approach to testing is fraught with limitations. First, the actual process of testing nationally has limited racial groups provided to patients, variation in reference equations used by individual hospitals and health systems, and inconsistent reporting of race-corrected and uncorrected values to providers. Second, result interpretation demonstrates wide variation in “race-corrected” predicted FEV1 values both between and within groups depending on the race-correct equation used, which can vary widely. This is particularly important when considering that % predicted FEV1 is used for evaluation of lung transplantation candidacy and prediction of postoperative pulmonary function such as in the case of lung resection for cancer. Postoperative pulmonary function in the setting of cancer resection is determined by the % predicted FEV1 preoperatively and the complement of bronchopulmonary segments remaining following resection (the predicted postoperative FEV, or PPO FEV1). In Table 1, %predicted FEV1 based on different reference equations for patients is provided and predicted postoperative %FEV1 for a right upper lobectomy. This table highlights wide variation dependent on equation and racial group but also that use of race-based equations has differential impacts on lung transplantation evaluation and lung cancer resection within racial groups. For instance, a lower predicted %FEV1 would improve candidacy for lung transplant but make it appear as though a right upper lobectomy was riskier in terms of postoperative pulmonary function. This is particularly of importance in the context of long-standing racial disparities for resection for lung cancer. For instance, decade's worth of research has demonstrated that Black patients are significantly less likely to receive definitive resection for lung cancer even after adjustment for clinical and social factors.13 The removal of race correction in spirometry may in fact exacerbate these disparities if changes result in Black patients having lower predicted FEV1 and potentially re-categorize Black patients as “nonoperative” candidates. Thus, the shift to race-neutral spirometry with elimination of race-correction cannot be done in isolation and will require alternative diagnostic testing and education of the surgical community to limit potential unintended consequences and to understand an individual patient's true pulmonary function.

TABLE 1 - 67-year-old Man with Height of 70 inches/178 cm and FEV 1 of 2.5L on Spirometry
White African American Mexican American Asian American
Predicted FEV1 (liters)
 GLI Race Corrected 3.3 2.8 3.1 3.1
 NHANES Reference or Corrected value 3.4 3.0 3.5 3.0
% Predicted FEV1
 GLI Race Corrected 76% 89% 81% 81%
 NHANES Reference or Corrected value 74% 83% 71% 83%
Postoperative %Predicted FEV1 Following Right Upper Lobectomy
 GLI Race Corrected 64% 75% 65% 65%
 NHANES Reference or Corrected value 62% 70% 60% 70%
Global Lung Function Initiative Calculator recommends using the Other/Mixed racial category for Asian American and Mexican American.7,8
NHANES Reference Values were used for Caucasian, African American and Mexican Americans and the 0.88 corrected value for Asian Americans.6

FUTURE DIRECTIONS

The persistent use of race-corrected equations will continue to impact the surgical care of patients requiring lung resection or lung transplantation. Specifically, the evaluation of surgical risk, already fraught with subjectivity, will continue to be skewed by racial group without a concerted effort to move away from using race in pulmonary function test interpretation. To do this, surgeons performing pulmonary surgery, healthcare systems and researchers must do five things. First, surgeons should educate themselves about the current spirometry testing done within their practice setting, so they can understand how individual hospital labs and their correction algorithms might be skewing their risk assessments. Second, research evaluating social disadvantage and structural racism as well physical measurements such Body Mass Index and sitting height as mechanisms for differences in lung function are necessary. Third, empiric research is needed to understand the association of race correction in spirometry and disparities lung transplantation listing, resection for lung cancer, and surgical outcomes. This will be challenging given transplant center or hospital level variation in race-correction equations used and complex modeling required for understand how race-correction impact lung allocation scores for lung transplantation listing, but it is a necessary first step. Fourth, surgical societies should provide formal recommendations regarding using race-corrected spirometry results currently being used nationwide for common thoracic operations and anticipate the need for a transformation of these recommendations as race-correction in clinical testing is eliminated. These recommendations must delineate how to interpret race-corrected spirometry compared to other pulmonary function tests such as diffusing capacity testing. There should also be clear guidance about the utility of additional pulmonary function testing besides spirometry given the potential for race-neutral equations to potentially worsen risk assessments of racial and ethnic groups already known to have disparities in surgical care. Finally, hospital systems should move towards abolishing race correction in pulmonary function testing with insight from thoracic surgeons and pulmonologists regarding standardized pathways and diagnostic testing to allow for equitable assessments of pulmonary function.

CONCLUSIONS

The current movement to remove race-correction in spirometry used for pulmonary function tests will have significant implication for all patients with pulmonary diseases requiring surgery. It is incumbent on the surgical community to interrogate the current role of race-correction in pulmonary function testing, and what impact it has on our individual surgical decision making. We need to prepare to change a fundamental clinical tool to make it more equitable for all patients.

REFERENCES

1. House Committee on Ways and Means. Fact Versus Fiction: Clinical Decision Support Tools and the (Mis)Use of Race: A Majority Staff Report. 2021. Available at: https://waysandmeans.house.gov/sites/democrats.waysandmeans.house.gov/files/documents/Fact%20Versus%20Fiction%20Clinical%20Decision%20Support%20Tools%20and%20the%20%28Mis%29Use%20of%20Race%20%282%29.pdf. Accessed December 20, 2021.
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Keywords:

lung cancer surgery; lung transplantation; pulmonary function test; race

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