For decades, clinical algorithms that were used to diagnose disease have included race as a variable. Over the past several years, growing recognition that this may lead to diagnoses being entirely missed or undertreated in certain racial groups has led some doctors and researchers to push to remove race from these algorithms. But change has come slowly to the medical system, in part because clinicians don’t fully know what the ramifications of changing algorithms that are so central to their work will be.
A new analysis, published in the New England Journal of Medicine, estimated the impacts of removing race from spirometry, a test used to measure lung function. Historically, physicians in the U.S. expected Black people to have lower lung function, so algorithms that analyze spirometer data have corrected for this by using a different scale. The new study found that switching to a race-neutral equation would result in classifying the lung disease of nearly half a million Black Americans as more severe and increasing disability payments to Black veterans by more than $1 billion.
There are tradeoffs with changing such an important algorithm, but overall the new study “provides good support for the change from race-adjusted to global standards for pulmonary function test interpretation,” says Neil Schluger, a pulmonologist at New York Medical College, who was not involved with the research.
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The spirometer is a device that measures the amount of air a person can blow in one breath—a gauge of how well that person’s lungs are functioning. The device has a long history of being used to legitimize racist views of lung function, says Lundy Braun, a historian at Brown University, who has written a book on the subject. Thomas Jefferson once speculated that Black people had different lung function than white people. So when spirometers—which were developed in Europe—were first used in the U.S., physicians here assumed their measurements differed by race, Braun says.
The idea persisted to the present day. But there’s been a growing recognition that “putting race into an algorithm is a flawed concept in that it is assuming something biologic about a person, even though we know that race is not representative of biological differences,” says Sidra Bonner, a general surgeon at the University of Michigan.
Doctors have been working to remove race from a slew of other clinical calculations. Algorithms used for determining heart disease, kidney disease, cognitive testing, diabetes screening and cancer screening have all used race in the past. Race has been removed from some of these measures—most notably estimated glomerular filtration rate, or eGFR, a measurement of how well a person’s kidneys are functioning.
Previously, the calculations for eGFR allowed for higher levels of creatinine, a waste product from the kidneys, in Black individuals compared with white ones. This led to Black people receiving fewer kidney disease diagnoses, lower doses for prescription drugs and less eligibility to see kidney specialists and receive kidney transplants, the researchers who published the new study on spirometry found in earlier investigations. Correcting this was relatively straightforward because eGFR results provided two values—one for Black people and one for everyone else—so clinicians could just move to using the latter.
Researchers hope a similar removal of the race variable will happen for spirometry, but that change might be harder to make. Currently, most doctors have no idea whether they are using a race-corrected spirometry algorithm or not because the measurement software does so automatically.
“We have since learned so much about the unequal distribution of socioenvironmental factors that cause lung damage,” says James Diao, a medical student at Harvard Medical School and lead author of the new study. “Beyond the many other drawbacks of using race, these findings have cast doubt on the justification of treating racial differences as healthy or normal.”
In 2021 both the American Thoracic Society and European Respiratory Society stated that adjusting for race in lung function estimates was not appropriate. The following year a group called the Global Lung Function Initiative created a race-neutral equation for lung function.
Diao and his colleagues found that the race-neutral equation was similarly accurate at predicting respiratory disease—including chronic obstructive pulmonary disease, asthma and other chronic respiratory diseases—as the previous equations. Using data from more than 300,000 people from across the U.S. and the U.K., the researchers compared the outcomes of using the old, race-conscious test with the newer one that removed race—then applied those differences to the entire U.S. For Black Americans, this meant reclassifying respiratory disease as more serious and increasing the number and amount of disability payments. But even these changes, which could affect millions of people, don’t encompass the full implications of removing race from spirometry, the authors of the new study say.
“Spirometry data is so deeply embedded into respiratory evaluation, and there are dozens of other affected outcomes that we were unable to quantify,” says Arjun Manrai, an assistant professor of bioinformatics at Harvard Medical School and senior author of the new study. These include the effects on people’s eligibility for clinical trials, insurance coverage and certain jobs.
“This study highlights that we need to think carefully about the ramifications of these changes because once we make these changes, clinical care is going to change, and people’s financial benefits are going to change,” says Thomas Valley, a pulmonologist at the University of Michigan.
He notes that there are trade-offs with the race-neutral calculation, however. For example, according to another study that was published last year, when doctors were presented with hypothetical scenarios using race-neutral or race-corrected data, they were less likely to recommend a more invasive, but also more effective, surgery to remove lung tumors in Black people with race-neutral lung function scores. Because clinicians have historically artificially increased the spirometry measurements of Black patients, surgeons have felt more comfortable removing more of such patients’ lung. With race-neutral scores, surgeons in the 2023 paper were more likely to opt for removing a smaller portion of the lung. But in some cases, this might be less effective at curing a person’s cancer. These findings suggest that doctors may need to rethink how they use spirometry data without race corrections in treatment decisions.
Several researchers who were not involved with the study agree that the new findings show that clinicians should move away from using race in their calculations. They also point to larger issues in the field, however. The race-neutral equation has been found to be as good at predicting respiratory symptoms as the old algorithm. But if the race-based equation is flawed, it might signal “that perhaps what we’re using isn’t good enough..., that perhaps we need better measures to assess how bad someone’s respiratory symptoms are,” Valley says. “This line of work highlights the need to go back to the drawing board to better measure lung function in a way that correlates with important outcomes to patients.”