Responding to complaints that pulse oximeters that measure blood oxygen levels are less accurate in people with darker skin tones, the Food and Drug Administration Monday released long-awaited guidance proposing how manufacturers should test and label these devices.
The document recommends testing the devices on far more people and provides clearer direction on the makeup of populations — and of skin tones — they should be tested on. Previous guidelines asked for 200 data points; the new guidelines suggest manufacturers submit 3,000; they also increase the suggested sample size for studies of pulse oximeters from 10 people to 150 or more.
Rather than relying on those testing the devices to judge skin tones, the draft guidance suggests manufacturers should use both the newly developed Monk Skin Tone scale and another scale, called the individual typology angle (ITA), which is based on spectrophotometric measurements.
The FDA stipulates that at least 25% of subjects should be in each of three groups: those with light, medium, and dark skin tones, and that half the participants in the dark-skin tone group include subjects with very dark skin. The guidance also stated that if equal performance is demonstrated, the device package insert should include a prominent statement conveying “This pulse oximeter has been evaluated to perform comparably across groups of individuals with a wide variety of skin tones.”
The new guidance comes decades after studies showed that the widely used devices work less well on patients with darker skin and more than four years after new research on the problem was published during the Covid-19 pandemic when the devices were instrumental. Subsequent studies have shown the problem has led to some patients not being admitted into emergency rooms for severe cases of Covid, or not receiving supplemental oxygen they needed while being treated in ICUs, and may have led to a higher number of cases of organ failure and death for patients with darker skin.
“So many people have been waiting for this. I think it’s definitely a great development and a good step in the right direction,” Sara Gerke, an associate professor at the University of Illinois College of Law, told STAT. “FDA is now really clearly addressing the issue of racial bias.”
Previous guidance released in 2013 advised that the devices be tested on “at least two darkly pigmented” or 15% of all subjects, whichever is larger, and did not specify how skin tone was to be measured, which critics said allowed for device manufacturers to not include the darkest skin tones where devices may work less well.
The guidance comes after a 2021 safety communication from the agency about the devices, several days-long advisory board meetings, a detailed white paper, and extensive studies conducted at the FDA’s behest in a specialized lab.
“Our draft recommendations are based on the best available science to help address concerns of disparate performance of pulse oximeters based on an individual’s skin pigmentation,” Michelle Tarver, director of the FDA’s Center for Devices and Radiological Health, said in a statement.
The new guidelines are not legally enforceable but “describe the Agency’s current thinking on a topic and should be viewed only as recommendations,” the document said. Such guidelines are generally followed by manufacturers seeking agency approval to market devices. The agency is soliciting public comment on the guidelines for the next 60 days before making them final.
Tom Valley is a physician who has been eagerly awaiting the new guidance. An ICU physician and associate professor at the University of Michigan, Valley was a co-author of a 2020 New England Journal of Medicine paper that brought renewed attention to the issue of racial disparities in how well pulse oximeters worked. While he called the proposed guidance “an important step,” he said he worried it did not go far enough.
“One reason why this problem has persisted for so long is that pulse oximeters are rarely, if ever, tested on the patients for whom we most need to know their oxygen levels — sick patients, often in the hospital,” he said. While the agency suggested manufacturers could use “real-world data” in some cases, such data are difficult and expensive to collect, and Valley noted the draft did not give many details on how that data might be collected. “If we want to know for sure that devices work well for the patients they’re intended for, we need to make sure that we’re actually testing these devices on those patients,” he said.
The agency also addressed concerns about devices that may not work equally on all skin tones but were previously approved under the less onerous 501(k) submission pathway, where manufacturers need only prove their devices are as safe and effective as those already on the market. The agency said it believed that some devices now in use may need “significant hardware or software modifications” to show they work well on all skin tones, but that others would probably meet the new guidelines without such changes.
The agency called on manufacturers to gather clinical data showing the efficacy of these devices on all skin tones and submit that data and a new label showing the device performs well on all skin tones in a new 501(k) submission, which would be reviewed in 30 days. The agency said it would maintain a list of devices that have been shown to work equally well on all skin tones on its website “to further promote transparency.”
Carmel Shachar, an assistant professor of clinical law at Harvard School of Law, said the public website would be a carrot, not a stick, approach for the FDA to use with manufacturers. “You have this label saying, ‘My device is not biased.’ You have this website where, ideally, physicians as well as whoever in the hospital is in charge of ordering devices will seek out devices with this label, will go to that list of devices and pick from those devices,” she said.
Valley said such information would also prove useful to physicians. “What we all want is to know which pulse oximeters we should be using every day,” he said.
The draft guidelines apply to devices used in hospitals and doctor’s offices and do not apply to devices sold directly to consumers for wellness or athletics, which are not subject to FDA review. Gerke said she thought these over-the counter-devices should be subject to the same requirements to prove they work equally well for all since they are often used by consumers for medical reasons.
Lawmakers have urged the FDA to act on the issue since 2021, and a handful of pulse oximeter manufacturers, including Medtronic, have settled a lawsuit brought against them by a clinic in Oakland, Calif., that serves a large Black population.
In a statement regarding the new guidance, Medtronic officials said they were “deeply committed to achieving equitable care for all patients” and said the company was already working on testing devices using the Monk Skin Tone scale to ensure equity and planned to provide comments to the FDA.
Many who rely on the devices remain frustrated with the time the agency has taken on the issue and doubt voluntary guidance will spur manufacturers to improve the accuracy of oximeters without enforcement.
Theodore Iwashyna, a critical care physician and professor at Johns Hopkins University, was a co-author on a JAMA paper released last week showing little action was taken by device makers following the agency’s 2013 guidance on the devices. “Without enforcement and compliance,” he said Monday, “I am not sure why we would anticipate these ‘proposed new draft recommendations’ would result in better products, and therefore better, more equitable care.”
This story has been updated with a comment from Medtronic.
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