Key medical devices are failing to diagnose Black patients accurately, research shows

A pulse oximeter gives a reading of 99% blood oxygen saturation level and a heart rate of 84 beats per minute for a Black patient.
A Black woman uses a pulse oximeter to check her blood oxygen saturation level and heart rate. (Getty Images)

For decades, some health care devices that are used to diagnose and treat patients have failed to provide adequate care for Black people, according to several research studies.

A group of University of Michigan researchers found that Black patients' blood oxygen levels are three times more likely to be overestimated by pulse oximeters than white patients'.

“Pulse oximeters are less accurate for Black individuals, because [they] were historically designed and calibrated for individuals with lighter skin tones,” Thomas Valley, an assistant professor at the University of Michigan, told Yahoo News.

The small devices were created in the 1970s and are used in homes, clinics and hospitals to measure a patient's oxygen level. A reading of 100% is considered a normal reading, while any number below 96% gives cause for concern.

“It has been traditionally overestimating that value, and given the false impression that [Black] people actually have sufficient oxygen, when in fact they don't,” Kimani Toussaint, the associate dean at Brown University, told Yahoo News.

At the peak of the pandemic, such inaccuracies could be life-threatening. A 2022 Johns Hopkins study found that more than 20% of Black and non-Black Hispanic patients were likely not to have their eligibility for treatment recognized by pulse oximetry, which was used as a screening tool for COVID-19 symptoms.

In that study, Black patients were found to be 29% "less likely to be recognized as eligible for COVID treatment than white patients,” Rutendo Jakachira, a second-year Ph.D. student at Brown University, told Yahoo News.

A Black woman wearing a mask is seated as a medical technician, in mask and visor, prepares a treatment.
A Black woman waits in a clinic during the COVID-19 epidemic. (Getty Images)

Indigenous, Latino, Pacific Islander and Black Americans have a significantly higher COVID-19 mortality rate than white or Asian Americans, data shows.

“Inaccurate pulse oximeters lead to Black patients receiving less oxygen, Black patients having life-saving treatments for COVID-19 delayed, Black patients being at higher risk for more failing organs, and Black patients being at higher risk of death,” Valley said.

“That’s particularly important because the concern was that some folks during COVID were not treated because they were denied treatment, because the pulse oximeter was used as a screening tool,” Toussaint added.

Doctors can draw blood to determine an accurate reading of a patient’s oxygen level, but the process is challenging.

“The way they draw the blood is a bit painful. And they usually have to wait several minutes to like a half hour to get the results of the oxygen level in your body,” Toussaint said.

In the meantime, Toussaint and Jakachira are working with researchers at Brown University to develop a device that will measure oxygen levels for all skin complexions. Now in the prototype stage, the device is large, about the size of a shoebox.

“Once we are able to test it in the hospital on critically ill patients, to confirm whether the pulse oximetry readings that we obtain are accurate for patients of all skin tones who are critically ill, then we will be able to miniaturize it,” Jakachira explained.

Concerns over the devices have also caught the attention of the Food and Drug Administration. In 2021, the agency released a safety warning concerning the use of pulse oximeters, and earlier this month, the Medical Devices Advisory Committee met to review the data. It now plans to release a revision of the recommended guidance.

Pulse oximeters are not the only devices that return inaccurate measurements of the health of Black patients. Thermal thermometers can also give unreliable readings based on the ethnicity of the patient, researchers have found.

A technician in a white coat holds up scanner to project a circle of points of light onto the forehead of a Black woman wearing a surgical mask, as other people in masks line up behind her in a large room in an office with overhead lights.
A Black woman receives a temperature check before she starts work. (Getty Images)

Researchers from Emory University and the University of Hawaii recently released a study analyzing the performance of temporal thermometers in a sample of more than 4,000 Black and white patients.

“We found that in white patients, it doesn't matter whether you use an oral or forehead thermometer, you get the same measurement. In Black patients, it absolutely matters," Sivasubramanium Bhavani, an assistant professor at Emory University, told Yahoo News. Forehead thermometers had a 26% lower odds of missing fevers in Black patients that oral thermometers detected, he said.

Such omissions could be deadly. “It’s dangerous because when a hospitalized patient has a fever, a doctor is notified. And the doctor might evaluate the patient sooner, they might give antibiotics faster, or even transfer them to an ICU quicker,” Bhavani said.

Given that thermal thermometers miss nearly 1 in 4 fevers in Black patients, researchers say oral thermometers are the most effective tools to use for an accurate measurement.

“As physicians, and I think, as patients, we kind of assumed that a device that’s as universal as a thermometer would have been rigorously validated across a diverse cohort of patients. So we were surprised that we could find this big of a discrepancy,” Bhavani said.

Similarly, pulse oximeters and thermal thermometers use infrared technology to measure a patient's oxygen levels and temperature. Now researchers are concerned about other devices that may also give inaccurate readings depending on the ethnicity of the patient.

“I could absolutely imagine that there are other devices out there that use similar kinds of technology, that we'd want to be extra certain to work just as well in patients with dark skin colors,” Philip Verhoef, a medical practitioner in Hawaii, told Yahoo News.

Verhoef says that as a result of the alarming discrepancies in the results, he is now careful not to rely on the initial data for his patients.

“It's just really disappointing. I think many of us work hard to sort of combat disparities in care [and] in medicine. And it's like, even the tools that we have for caring for patients are inherently biased, and that just makes it that much harder to provide care for everyone in an equitable fashion,” he said.