Does an oximeter know your skin colour? Here's why UK is probing racial bias in medical devices

UK Health Secretary Sajid Javid has announced that a review will be launched of medical devices in light of findings that readings of the ubiquitous pulse oximeter are less accurate when it comes to people of darker skin colour, pointing to the possibility that it may have led to thousands of avoidable deaths during the Covid pandemic.

Pulse oximeters track oxygen saturation in blood so that urgent medical response can be provided upon a dangerous drop in levels. However, these devices could have failed to reflect drops in blood oxygen levels of people from ethnic groups, something that has set alarm bells ringing for UK authorities. Here’s what you need to know.

What's the apprehension over medical devices?

As the pandemic dragged on from one year to the next, it wouldn’t be too wrong to say that the pulse oximeter became to Covid-19 what the thermometer is to viral fever. However, experts have found that readings from these devices cannot be taken at face value when it comes to people with darker skin tones.

Clipped to the finger, the oximeter indicates the oxygen saturation level in blood. With the propensity of the novel coronavirus to cause breathing problems, the oximeter became a vital aid for detecting a drop in blood oxygen levels. But research shows that these devices can overstate the level of oxygen in the blood of people with darker skin.

Reports said that could be because these devices work by passing light through blood and skin pigmentation could have a bearing on how light is absorbed. BBC quoted Dr Michael Sjoding of the University of Michigan in the US, who led a study on pulse oximeters, as saying his team found that “at least twice, perhaps three times as often, the device is less accurate on black patients".

That points to a possibility that inaccurate readings of a pulse oximeter contributed to grave complications in Covid treatment for a section of people and could also have been a factor in leading to avoidable deaths. UK Health Secretary Javid at least indicated that that might be the case. “I think possibly yes, yes. I don’t have the full facts," he told a BBC programme when asked if he thought flawed oximeter readings had led to deaths.

“These oximeters are being used in every country and they have the same problem and the reason is that a lot of these medical devices, some of the drugs, the textbooks, the procedures, most of them are put together in majority-white countries and I think there is a systemic issue," Javid added.

What is being done to address the bias in such devices?

Javid said the UK would be partnering with US authorities to investigate systemic racism and bias in medical devices as a way of arriving at an explanation as to why people from ethnic or racial minorities and women have worse health outcomes. Incidentally, Javid is the first UK health secretary of colour while his American counterpart, Xavier Becerra, is the first Latino to occupy that office in the US.

“There are research papers already on this and no one did anything about it," Javid said, referring to racial bias in medicine, adding though that even if it was not “deliberate", they highlight “a systemic issue potentially, with medical devices and it may go even further than that with medical textbooks".

The aim of the review — which will also focus on gender bias and addressing the issue of how medical services and devices can be made more accessible for women — is to come up with new global standards for medical devices, requiring for them to be tested on people of all races before being launched in the market.

However, BBC reports that the UK doctors’ union, British Medical Association (BMA), has urged that the review should go beyond just studying bias in medical equipment to delve into “structural issues" within healthcare that lead to inferior outcomes for ethnic groups.

How does bias creep into a medical device?

Announcing the review via an article in an English daily, Javid said that bias may be hard-wired into the processes and mechanisms that inform medical science.

“It is easy to look at a machine and assume that everyone’s getting the same experience. But technologies are created and developed by people, and so bias, however inadvertent, can be an issue here too. So questions like who is writing the code, how a product is tested and who is sitting around the boardroom table are critical — especially when it comes to our health," he wrote.

The health impacts of socio-economic factors linked to race and ethnicity are well-known and have been seen as an explanation for more severe effects of Covid-19, and other diseases, in certain communities. For example, noting the role of occupation as a risk factor for Covid-19, the US Centre for Disease Control and Prevention (CDC) says, “People in racial and ethnic minority groups often work in essential settings, such as healthcare facilities, farms, factories, grocery stores, and public transportation. Working in these settings can lead to more chances of exposure to Covid-19."

However, experts also talk about the presence of “implicit bias" in health systems, which can be described as “unconscious attitudes and stereotypes held towards other people". An article in US News & World Report touches on documented instances of bias in healthcare, pointing to how “black women were less likely than white women to receive radiation therapy… after a lumpectomy" and the lower likelihood of black patients hospitalised for a heart attack to “receive certain types of often-prescribed medications" than white patients.

The US medicines regulator Food and Drug Administration (FDA) also highlights another kind of basic bias, that in the testing of medicines. In a 2011 white paper, it had noted that African‐Americans represented 12 per cent of the US population but only 5 per cent of clinical trial participants while Hispanics accounted for only 1 per cent of clinical trial participants even though they make up 16 per cent of the population.

UK health secretary Javid said that the pandemic has only served to put the focus on such discrimination.

“The pandemic has brought this issue to the fore, but the issue of bias within medical devices has been ducked for far too long… We urgently need to know more about the bias in these devices, and what impact it is having on the frontline," he said.

So, are pulse oximeters to be avoided?

What experts have advised is more awareness of the limitations of these devices. Reports say that UK authorities updated the guidance for patients from black, Asian and other ethnic minority groups in light of reports of bias in pulse oximeters. People from these communities should continue using oximeters, it was said but would need to consult a healthcare professional.

Javid echoed the same point of view, saying that there are “very high standards for these technologies in this country — and people should keep coming forward for the treatment they need."

What do we know about race and COVID-19?

Reports said that ahead of Javid’s announcement of the racial bias review, government health data in England showed that people of colour were two to four times more likely to die from Covid-19 than white people while those of Asian descent were 1.5 times more likely than their white counterparts to catch an infection.

Further, a report by British researchers said that the majority of people of South Asian descent carry a gene that makes them extra vulnerable to severe Covid-19. But while the genetic factor was cited to explain the relatively high rate of deaths and hospitalisations witnessed in the UK among people from the subcontinent, authors of the report also pointed to the likelihood of other factors being at work, like socio-economic background.

In the US, reports say that while 1 in 595 Indigenous Americans died from Covid, the proportion increased to 1 in 735 for Black Americans, 1 in 1,000 for Latinos and 1 in 1,030 for white Americans with structural factors like housing inequality, access to healthcare, and poverty being seen as having a strong bearing on the disproportionate impact of the pandemic on some communities.