Two months after Democratic lawmakers expressed concern about potential racial disparities in pulse oximeter readings — calling the issue a matter of “life or death” — the Food and Drug Administration on Friday issued a public warning about the devices, acknowledging they had “limitations.”
The alert comes decades after researchers first identified potential inaccuracies with the devices when used on people of color and months after a series of new studies produced fresh data underlining the problem. Most recently, researchers at the University of Michigan published a December 2020 letter in the New England Journal of Medicine that found oximeters were nearly three times as likely to miss hypoxemia in Black patients compared with white patients.
“Be aware that multiple factors can affect the accuracy of a pulse oximeter reading, such as poor circulation, skin pigmentation, skin thickness, skin temperature, current tobacco use, and use of fingernail polish,” the FDA’s alert reads.
It does not explicitly mention racial disparities in the accuracy of the devices, likely disappointing clinicians and patients who have sought to draw attention to the issue.
“It’s noticeable that the word ‘race’ or ‘racial’ is not mentioned in the FDA communication,” said Thomas Valley, a pulmonary critical care physician and an author of the NEJM letter. “At the same time, what we found was a difference between Black and white patients. We don’t know exactly why that difference existed, we presume it to be skin tone.”
Pulse oximeters, which measure oxygen levels, have emerged as a particularly useful clinical tool amid the Covid-19 pandemic because of the way the virus interferes with the body’s natural ability to process oxygen. In hospitals, the devices play a critical role in making decisions about patient care. And late last spring, after several practitioners suggested the devices could be helpful to have on hand at home (similar to the way one might want to keep a thermometer in the drug cabinet, for example), at-home versions of the devices began flying off drugstore shelves and rapidly selling out on Amazon and other online sites.
But the December paper — and its reference to a series of earlier studies documenting the same problem, including one published in 2005 — raised alarms among researchers and clinicians, who said they were frustrated to learn the issue had not been addressed in a substantive way after 15 years.
“To not be confident in the accuracy of that number, and to depend on a device that may have bias toward a certain population is really troubling,” Utibe Essien, a physician and an assistant professor of medicine at the University of Pittsburgh School of Medicine, told STAT earlier this month.
In response to these concerns, William Maisel, director of the Office of Product Evaluation and Quality at the FDA’s Center for Devices and Radiological Health, told STAT the agency was reviewing the available data and would consider further studies if necessary. He said the FDA is broadly confident that hospital-based oximeters are highly accurate, but added the same might not be true for devices sold online and in drugstores, which the agency doesn’t review or approve.
Michael Sjoding, a pulmonary physician at Michigan Medicine and an author on the NEJM letter, said he was happy the FDA stressed the importance of not over-relying on pulse oximeters to make medical decisions in its statement. He added, though, that he thought the absence of an explicit mention of race was a “missed opportunity.”
“Given the limitations of our paper … I suspect the FDA wants to be fairly guarded in their messaging about racial disparities in pulse oximeter accuracy and focus more on the problem of pulse oximeter inaccuracy more generally,” he said.