COVID-19 sufferers with darker skin died at higher rates than lighter-skinned patients during the height of the pandemic, and now two Black doctors are presenting evidence about one factor that could have contributed to that disparity. Doctors Stephanie Brown and Noha Aboelata say in a study published last August the pulse oximeter is biased.
“The technology itself appears to be flawed and does not take into account skin tone,” Aboelata told Bay Area TV station KGO last month.
The pulse oximeter measures a person’s blood oxygen level, a key measurement when determining COVID-19 treatment. The device is usually placed on a fingertip. It uses light beams to estimate the oxygen saturation of the blood and the pulse rate.
“The oxygen reading in the blood determines your treatment trajectory for COVID,” Dr. Brown said.
“Total cumulative data show that Black, Hispanic, Native American, and Pacific Islander people have experienced higher rates of COVID-19 cases and deaths than white people when data are adjusted to account for differences in age by race and ethnicity,” the Kaiser Family Foundation reported.
“We felt like something else had to be happening, since whites with diabetes and kidney disease, for example, were experiencing lower rates of death and disease severity than Blacks even when they had the same clinical risk factors,” Brown said.
In December 2020, the New England Journal of Medicine was among the first to refocus the spotlight on issues with the pulse oximeter to a new generation of medical researchers, although Brown said research into the device’s accuracy goes back 30 years.
“Questions about pulse oximeter technology have been raised, given its original development in populations that were not racially diverse,” the study said.
Washington State University Elson S. Floyd College of Medicine student, Joel Bervell, focused on the faulty device in a viral TikTok video he posted in 2020, adding increased scrutiny on the device. He gained national attention for his TikTok channel he uses to highlight racial disparities in medicine.
“For me, it was a moment where I said, how come we don’t know about this, especially when this could affect so much of the population, myself included,” Bervell said.
Brown and Aboelata were part of the study team that included Sylvia E K Sudat, Paul Wesson, Kim F Rhoads, Alice R Pressman, Aravind Mani, and Kristen M J Azar.
The study it explains how the pulse oximeter works and where the breakdown occurs in people with darker skin. The light beam emitted by the pulse oximeter passes through tissue and blood. The amount of light not absorbed is used to estimate the blood’s oxygen saturation. The pulse oximeter’s accuracy can be impacted by skin features, including “thickness, pigmentation, and temperature,” according to the findings.
The study highlighted Black people with COVID-19 “were nearly three times more likely” than white people to have hypoxemia, low blood oxygen level, when the pulse oximeter reading said otherwise.
Systemic overestimation of the blood oxygen level among Black COVID-19 patients can lead to delays in care, contributing to health disparities, the report says.
Brown says patients with oxygen levels 95 percent or higher are typically sent home from the hospital while patients with 94 percent oxygen levels and lower receive extra treatment.
The research suggests Black COVID patients who should have received more intensive COVID-related care were instead sent home from the hospital because their oxygen readings did not warrant extra treatment which increased their risk of death.
The delays Black COVID patients experienced include increased time accessing dexamethasone (swelling, redness, pain) and supplemental oxygen treatment lasting 37-minutes and 4.5 hours respectively.
“To see someone in front of my face, who looks to be working harder to breathe, and seems to be sicker than what I see in front of me. That’s a tough kind of mind game to play on a daily basis,” Brown told KGO.
“When we found out that this tool in and of itself was biased, and was showing readings in the normal range more frequently for darker skinned people, when in fact, their oxygen was below the normal range, that is just devasting,” Aboelata said.
The study was conducted by researchers at Sutter’s Institute for Advancing Health Equity in collaboration with clinicians and researchers from the Roots Community Health Center and the University of California San Francisco.
Aboelata is the founder and CEO of Roots Community Health Center. Brown is the clinical lead for Sutter Health’s Institute on Advancing Health Equity.
The Food and Drug Administration issued recommendations for healthcare providers on pulse oximeters and their limitations last November.
The pulse oximeter market is expected to hit $2.5 billion by 2030, according to a report released by Global Market Insights.
Brown urges medical providers and users relying on the pulse oximeter to “maintain a high index of suspicion” particularly for patients with darker skin tones.
An alternative to measuring blood oxygen levels can be done with an arterial blood gas (ABG) which draws blood from an artery in the wrist. Brown says this procedure can be painful, but darker-skinned patients could be subjected to the procedure for more accurate blood oxygen readings, which she describes as “unfair.”
“The findings underscore the fact that bias is not only human it can be engrained in the devices and tools clinicians rely on,” Brown said in a statement.
