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How software bias leads to under-diagnosis in black men’s lung problems

Software bias in a common medical test for lung function is leading to fewer black patients getting care for breathing problems, according to research which found that as many as 40% more black male patients in the study might have been diagnosed with breathing problems if diagnosis-assisting computer software were changed.

Doctors have long discussed the potential problems caused by race-based assumptions that are built into diagnostic software, and this study, published in JAMA Network Open, offers one of the first real-world examples of how the the issue could affect diagnosis and care for lung patients, said Dr Darshali Vyas, a pulmonary care doctor at Massachusetts General Hospital.

Vyas authored a 2020 New England Journal of Medicine article that catalogued examples of how race-based assumptions are used in making doctors’ decisions about patient care, reports AP News.

For centuries, there has been a misconception that there are natural racial differences in health, including one that black people’s lungs were innately worse than those of white people. That assumption ended up in modern guidelines and algorithms for assessing risk and deciding on further care. Test results were adjusted to account for – or “correct” for – a patient’s race or ethnicity.

The latest study focused on a test to determine how much and how quickly a person can inhale and exhale. It’s often done using a spirometer – a device with a mouthpiece connected to a small machine.

After the test, doctors get a report that has been run through computer software and scores the patient’s ability breathe. It helps indicate whether a patient has restrictions and needs further testing or care for things like asthma, chronic obstructive pulmonary disorder or lung scarring due to air pollutant exposure.

Algorithms that adjust for race raise the threshold for diagnosing a problem in back patients and may make them less likely to get started on certain medications or to be referred for medical procedures or even lung transplants, Vyas said.

While physicians also look at symptoms, lab work, X-rays and family histories of breathing problems, the pulmonary function testing can be an important part of diagnoses, “especially when patients are borderline”, said Dr Albert Rizzo, the chief medical officer at the American Lung Association.

The new study looked at more than 2 700 black men and 5 700 white men tested by University of Pennsylvania Health System doctors between 2010 and 2020. The researchers looked at spirometry and lung volume measurements and assessed how many were deemed to have breathing impairments under the race-based algorithm compared with a new algorithm.

Researchers concluded there would be nearly 400 additional cases of lung obstruction or impairment in black men with the new algorithm.

Earlier this year, the American Thoracic Society, which represents lung-care doctors, issued a statement recommending replacement of race-focused adjustments. But it also put a call out for more research, including into the best way to modify software and whether making a change might inadvertently lead to over-diagnosis of lung problems in some patients.

Vyas noted some other algorithms have already been changed to drop race-based assumptions, including one for pregnant women that predicts risks of vaginal delivery if the woman had previously had a Caesarean section.

Changing the lung-testing algorithm may take longer, Vyas said, especially if different hospitals use different versions of race-adjusting procedures and software.

Study details

Global, race-neutral reference equations and pulmonary function test interpretation

Alexander Moffett, Cole Bowerman, Sanja Stanojevic,  et al

Published in JAMA Network Open on 1 June 2023

Key Points

Question How do race-neutral reference equations affect pulmonary function test interpretation?

Findings In this cross-sectional study of 8431 black and white individuals, the use of race-neutral reference equations for pulmonary function test interpretation, compared with the race-specific reference equations that are currently recommended, resulted in an increase in the percentage of black individuals identified with restrictive ventilatory impairments from 26.8% to 37.5% and an increase in the percentage of black individuals identified with nonspecific ventilatory impairments from 3.2% to 6.5%. The percentage of white individuals identified with restrictive impairments decreased from 22.6% to 18.0%, while the percentage of white individuals identified with nonspecific impairments decreased from 8.7% to 4.0%.

Meaning In this study, the use of race-neutral reference equations was associated with an increase in the prevalence and severity of ventilatory impairments in black patients.


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.

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 centre 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.

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.


AP News article – Black men were likely underdiagnosed with lung problems because of bias in software, study suggests (Open access)


JAMA Network Open article – Global, Race-Neutral Reference Equations and Pulmonary Function Test Interpretation (Creative Commons Licence)


See more from MedicalBrief archives:


UK investigation into racial and gender bias in medical devices


Race versus skin tone debate in resolving pulse oximeters’ false readings


Pulse oximetry accuracy varies between race groups – US cohort study


200-year-old race-based COPD diagnostic formula shown to be inadequate








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