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COVID-19 Symptom Lists and Detection Tools May Exhibit Racial Bias

O2 sensor on a Black patient's hand.

Grace Cary/Getty 

Key Takeaways

  • People with COVID-19 are told to watch for a blue discoloration of the face and lips. But Black patients are less likely to display this symptom than White patients.
  • Pulse oximetry measuring tools are also more likely to return inaccurate results for Black patients compared to White patients.
  • Experts argue that these examples indicate the need for increased racial equity in medical symptomatology and technology.

The Centers for Disease Control and Prevention (CDC) lists “bluish lips or face” (cyanosis) as an “emergency warning sign” of severe, potentially life-threatening COVID-19 infection. However, some social media users have pointed out that patients with dark skin would not be as likely to exhibit this symptom as lighter-skinned patients—even if they were seriously oxygen-deprived.

The observation indicates that the author of the CDC's list of COVID-19 warning signs may have assumed that readers would be White. The oversight—and others—have ignited a discussion about the role of racial bias in medicine and health care, particularly surrounding the COVID-19 pandemic.

Minority Communities Hard Hit by COVID-19

According to the APM Research Lab, COVID-19 has thus far killed one in 1,150 Latinx Americans, one in 800 Black Americans, and one in 750 Indigenous Americans. Comparatively, it has killed one in 1,325 White Americans and one in 1,925 Asian Americans.

One possible contributing factor is that some medical metrics of pulmonary health, as well as the tools designed to measure them, were developed with White rather than Black, Latinx, or Indigenous, patients in mind.

Hidden Biases in COVID-19 Symptomatology 

Michael Sjoding, MD, assistant professor of internal medicine in the division of pulmonary and critical care medicine at the University of Michigan Medical School, tells Verywell that while certain COVID-19 symptoms "are the same across races,” others are more visually apparent in people of one race than in people of another. 

For example, Sjoding says that lip discoloration is more “difficult to identify in darker-skinned individuals” than in lighter-skinned individuals. Instead, people with darker skin should be on the lookout for discoloration of the nails, gums, and the area around the eyes.

Michael Sjoding, MD

I think doctors should be aware that in darker-skinned patients, the pulse oximeter may be reading a few points higher than their oxygen level actually is, and adjust their treatment accordingly.

— Michael Sjoding, MD

Sjoding also says that the healthcare system may perpetuate “false beliefs about biological differences between Black and White patients” that could negatively affect the efficacy of their treatment.

“One example of this is that the symptom of pain may be underestimated or under-treated due to a false belief that Black patients feel less pain than White patients,” Sjoding says, adding that the issue is "not specific to COVID-19.” 

Hidden Biases in Medical Technology 

Earlier this year, Sjoding and four colleagues conducted a study on racial bias in pulse oximetry, a medical technique for measuring blood oxygen saturation levels.

Pulse oximetry uses the transmission of light through the tissue to divine the color of the blood on the other side. If it’s bright red, the patient is sufficiently oxygenated; if it’s dark red or purplish, the patient is insufficiently oxygenated.

The results of the study, published in the New England Journal of Medicine, suggest that pulse oximetry has a higher margin of error in Black patients than in White patients. Specifically, that pulse oximetry returned inaccurate results for Black patients three times as often as it did White patients—12% of the time compared to 4% of the time.

“I think doctors should be aware that in darker-skinned patients, the pulse oximeter may be reading a few points higher than their oxygen level actually is, and adjust their treatment accordingly,” Sjoding says.

Sjoding says that the racial disparity in pulse oximetry accuracy is likely related to the differing amounts of melanin, or pigment, in light and dark skin.

Melanin concentration is inversely correlated with the successful functioning of pulse oximeters. The lighter the skin, the lower the likelihood of an inaccurate result; the darker the skin, the higher the likelihood of an inaccurate result. 

In the conclusion of their study, Sjoding and his co-authors wrote: “Our findings highlight an ongoing need to understand and correct racial bias in pulse oximetry and other forms of medical technology."

Why the Difference Matters

Those few points could mean the difference between an adequate and inadequate medical response to respiratory distress. For example, pulse oximetry could indicate that a darker-skinned patient’s blood oxygen saturation levels are hovering around 92% when they are actually below 88%—the threshold for medical intervention.

“Given the widespread use of pulse oximetry for medical decision-making, these findings have some major implications, especially during the current coronavirus disease 2019 (COVID-19) pandemic," Sjoding and his co-authors wrote in their study. "Our results suggest that reliance on pulse oximetry to triage patients and adjust supplemental oxygen levels may place Black patients at increased risk for hypoxemia [abnormally low blood oxygen saturation levels]."

Sjoding recommends that doctors perform an arterial blood gas test—another way to measure blood oxygen saturation levels—instead of or in addition to pulse oximetry on dark-skinned patients. However, Sjoding adds that the arterial blood gas test “is much more invasive and painful” than pulse oximetry. 

What This Means For You

If you have dark skin, pulse oximetry is more likely to miscalculate your blood oxygen saturation levels. You might need to have an arterial blood gas test, which, while more invasive and painful, would provide a more accurate measure of your blood oxygen levels—which can be critically important if you get COVID-19.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

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Article Sources
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  1. Centers for Disease Control and Prevention (CDC). COVID-19: What to do if you are sick. Updated September 11, 2020.

  2. APM Research Lab. The color of coronavirus: COVID-19 deaths by race and ethnicity in the U.S. Updated December 10, 2020.

  3. Moran-Thomas, A. How a popular medical device encodes racial bias. Boston Review. Updated August 5, 2020.

  4. Sjoding MW, Dickson RP, Iwashyna TJ, Gay SE, Valley TS. Racial bias in pulse oximetry measurement. N Engl J Med 2020; 383:2477-2478. doi:10.1056/NEJMc2029240

  5. Malcolm, K. Racially biased oxygen readings could be putting patients at risk. University of Michigan Health Lab. December 16, 2020.