“It’s really shocking that the FDA has actually only issued a warning until 2021,” said Uche Blackstock, an ER physician and CEO of Advancing Health Equity. “And even in last year’s warning, they didn’t even mention racial bias, race or racism.”
The issue raises broader concerns about bias as technology is increasingly introduced into healthcare, and about the government’s ability to counteract it through regulation and oversight. Experts warn that disparate results among racial groups could worsen if the technology doesn’t work for all patients.
The Covid-19 pandemic has brought renewed attention to devices that are typically sensors at the fingertips of patients.
Michael Shoding, a pulmonologist and critical care physician at the University of Michigan, conducted the study. research published in December 2020 in the New England Journal of Medicine, which found that black patients between January and July 2020, and in 2014 and 2015, had low blood oxygen levels about three times as likely to go unnoticed as white patients. More than one in 10 black patients with oxygen saturation readings between 92 and 96 percent on a pulse oximeter actually had levels below 88 percent when measured by blood tests.
Normal levels range from 95 to 100 percent, while levels below 88 percent are considered dangerous.
Experts also say the problem points to a need to update guidance to compensate for the problem, as well as to diversify clinical trials.
According to Sjoding, the effect of the treatment is real. “This level of difference, if discovered and discovered, would change how we would care for a patient,” he explained. “You would give the patient more oxygen, or perhaps offer the patient a different treatment.”
Known and unknown
Experts say the erroneous readings are the result of how light is absorbed by different skin tones. According to Achuta Kadambi, an engineering professor at the University of California, Los Angeles, pulse oximeters work by shining light on a person’s skin and seeing how much light comes back.
Darker skin reflects less signal than lighter skin, which can skew pulse oximeter readings, he says. Kadambi, who has darker skin, has experienced similar problems with automatic soap dispensers that also use light to activate.
“The laws of physics are against darker objects, including skin,” Kadambi said, adding that algorithms are one way to solve this problem.
But the research results so far have limitations because they’re not all differentiated by oximeter type, said Amira Mohamed, a professor at the Albert Einstein College of Medicine. She also noted that generalizing by race can also be difficult.
“There are different types of blacks,” Mohamed said. “I am black myself, and this does not mean that it will affect me in the same way as, for example, my husband, who is black, is black.”
Mohamed also says that existing research has been done mostly on people with white skin, and that future research should focus on people who are more likely to be affected.
Current FDA guidance recommends that manufacturer studies include at least 10 individuals and “at least 2 subjects with dark pigmentation” or 15 percent of the total population.
Some experts argue that the FDA needs to increase this pool.
“Basically, you won’t have enough information about the accuracy of a device if you’re only testing it on two people,” Sjoding said.
More specific FDA guidance on oximeters is needed, said Ashraf Fawzi, a professor of medicine at Johns Hopkins University and lead author of the study. May Study Published in JAMA Internal Medicine found that providers are more likely to underestimate disease severity levels and delay treatment for black and Hispanic patients with Covid-19.
Fozi added that faster action from the agency would be helpful. The FDA should consider adding a warning label to devices, said Kimani Toussaint, an engineering professor at Brown University who is working on potential fixes.
Some experts, such as Blackstock, argue that pulse oximeters should be taken off the market. Others, like Mohamed, say that much more research needs to be done before any conclusions can be drawn.
“If we are concerned about someone’s breathing or someone’s oxygen level, it’s not safe to completely rely on a pulse oximeter and we always need to confirm it,” Mohamed said.
And fixing the problem in the devices themselves can be a daunting task.
An FDA spokesman said he is seeking to expand the available data on the problem by
funding a prospective clinical trial to inform any changes to the guidelines. The company hopes the research will help unravel the “sometimes conflicting data, including non-public information” that manufacturers have provided.
Meanwhile, researchers at Brown University are working on using single-wavelength light to bypass the skin. This study of healthy patients is at an early stage and has produced similar results to commercial devices. According to researcher Rutendo Jakachira, who works with Toussaint, inaccuracies tend to be more common in sicker patients.
The scientists are also considering using sound as a potential replacement for light as a new method for measuring blood oxygen levels.
Variety of clinical trials
Meanwhile, as technology plays an increasingly important role in healthcare, experts say clinical trials, in which people of color have long been underrepresented, need a major overhaul.
MPs are aware of this problem. House passed last month The FDA’s legislation on charges for the use of medical products, which contains language aimed at supporting the diversity of clinical trials.
Adrian Aguilera, head of the Digital Health Equity and Access Lab at UC Berkeley, said that in the absence of different participants, the results of the trials would not necessarily reflect what would happen in the real world.
Trials are traditionally conducted in person, requiring participants to be present on site, which can create barriers for low-income people or people with inflexible jobs. Lawyers want to use telemedicine attract a wider range of participants.
Companies should avoid “helicopter” research and instead spend time building relationships with community organizations and people on the ground, Aguilera said.
“An example of this pulse oximeter situation is if you don’t think about bias and racism from the start and don’t do it intentionally, it will be built into the technology,” Blackstock said.