Pulse oximeters don't work as well on darker skin, leading to flawed COVID care

new study published today in the American Journal of Epidemiology linked bias in the device used to measure blood oxygen, the pulse oximeter, to impacts on COVID-19 clinical care. The research revealed that pulse oximeter errors could have led Black patients to face a 4.5-hour delay in COVID-19 treatment. 

Blood oxygen level, most commonly assessed using the pulse oximeter, has been central to CDC treatment guidelines for COVID-19. The pulse oximeter was previously found to be less accurate in patients with darker skin, and a recent JAMA study revealed this resulted in a lower likelihood for COVID-19 treatment eligibility among several racial and ethnic groups. The latest analysis helps quantify the clinical impact of differential pulse oximeter accuracy on non-Hispanic Black patients suffering from COVID-19 – namely, that device inaccuracy was associated with delayed treatment for COVID-19 when compared with expected treatment under accurate blood oxygen measurement.

The study – led by PhD student Kristen Azar, RN, MSN/MPH, with contributions from Paul Wesson, PhD, and Kim Rhoads, MD, MPH, and conducted in collaboration with Sutter’s Institute for Advancing Health Equity (IAHE) and the Roots Community Health Center – found that Black COVID-19 patients could have delayed treatment due to the device’s inability to precisely read blood oxygen levels on darker skin. The analysis uncovered that overestimated blood oxygenation was associated with the following delays in COVID-19 care for Black patients:

  • Increased time to supplemental oxygen treatment (4.5 hours)
  • Increased time to dexamethasone treatment (37 minutes)
  • Lower hospital admission probability (3.1%)
  • Lower probability of receiving dexamethasone treatment (3.1%)
  • Lower probability of receiving supplemental oxygen treatment (4.2%) 

“Oxygen is one of the most frequently administered and essential medical therapies, and while flaws in the pulse oximeter device were raised during the pandemic, just how it actually affected patients remained unknown – until now,” said Stephanie Brown, M.D., MPH, clinical lead for the IAHE.

Industry analysts expect the use of the pulse oximeter to significantly increase in the coming years, making it critically important to continue studying and working to resolve this bias. The study’s authors identified several opportunities to address the device bias including revising the current guidelines for testing the device’s accuracy and for its use in the field, particularly when other clinical factors are inconsistent with a patient’s pulse oximetry measurements. The results also emphasize the need for additional investigation of the device given the broader implications beyond COVID-19 and its potential to exacerbate disparities for a wide variety of conditions that rely upon blood oxygenation readings to inform clinical decision-making, like emphysema and chronic obstructive pulmonary disease, or COPD.

“The findings underscore the fact that bias is not only human– it can be engrained in the devices and tools clinicians rely on, too. To build a more equitable healthcare system we must continue to not only uncover where bias exists in medicine, but also work to understand its impact on clinical outcomes and how it can be corrected. This is good medicine,” Dr. Brown added. 

The IAHE had previously analyzed the disproportionate impact of the pandemic on communities of color using electronic health record (EHR) data. Its latest research insights are an important extension of the original work. It reveals how bias embedded in the pulse oximeter device may have exacerbated existing disparities.  

“This study confirms our suspicions that other factors could be contributing to the disparities in deaths and severity of illness related to COVID, and delays in care for people of color in our community,” said Noha Aboelata, MD, CEO of Oakland, Calif.-based Roots Community Health Center and co-author of the study.

“Our research is just one part of an ongoing, multi-layered process that requires collective action across the healthcare industry to ensure that we are creating targeted interventions that take underrepresented groups into account,” said  Azar, who is also scientific medical director at IAHE. “Ultimately, our goal is to eliminate health inequities and drive better health outcomes for patients in our network and nationwide.”