Ethnic Discrepancies in Pulse Oximetry May Affect COVID Treatment

By Reuters Staff

June 01, 2022

NEW YORK (Reuters Health) - A new study confirms that pulse oximeters are more likely to miss low oxygen levels in Asian, Black and Hispanic individuals with COVID-19 compared with their non-Hispanic white peers, and suggests that this has consequences.

Under-diagnosis of hypoxemia may lead to significantly delayed or unrecognized eligibility for COVID-19 therapies among Black and Hispanic patients, which may contribute to worse outcomes, the study team reports in JAMA Internal Medicine.

Inaccuracies in pulse-oximetry measurement have come under increased scientific scrutiny over the past two years. A known design flaw of current pulse oximeters is that patients with darker skin (compared with lighter skin) are more likely to experience occult hypoxemia.

To investigate further, Dr. Asraf Fawzy of Johns Hopkins University, in Baltimore, Maryland, and colleagues took a look back at data from COVID-19 patients from five hospitals.

They had concurrently measured arterial blood oxygen saturation (SaO2) and pulse oximetry (SpO2) measurements for 1,216 patients (63 Asian, 478 Black, 215 Hispanic and 460 non-Hispanic white).

Occult hypoxemia (SaO2 <= 88% despite SpO2 of 92% to 96%) occurred in 19 Asian (30%), 136 Black (29%) and 64 non-Black Hispanic (30%) patients compared with 79 white patients (17%), the team found.

Compared with white patients, SpO2 overestimated SaO2 by an average of 1.7% among Asian, 1.2% among Black and 1.1% among non-Black Hispanic patients.

In a separate analysis of 6,673 patients, they showed that predicted overestimation of SaO2 levels by SpO2 was associated with a "systematic failure to identify Black and Hispanic patients who were qualified to receive COVID-19 therapy and a statistically significant delay in recognizing the guideline-recommended threshold for initiation of therapy."

"The association of under detection of occult hypoxemia with treatment delay cannot be disassociated from the multilevel injustices and persistent disparities underlying the worse COVID-19 outcomes experienced by patients of racial and ethnic minoritized groups," say the authors of a linked editorial.

"Historical neglect of patients of racial and ethnic minoritized groups and a diminished concern for their health outcomes may explain in part why this phenomenon - differential pulse oximetry accuracy - has been recognized for more than 30 years and has not been corrected," write Dr. Valeria Valbuena of the University of Michigan, in Ann Arbor, and co-authors.

"Although the device measurement error is real and based purely on optics, the decision to do nothing about a faulty device is a human one, and one that can and should be corrected," they add.

They say the next generation of oxygen monitors should be designed and tested to work equally well for different skin tones. They note that the design flaws of the pulse oximeter have been corrected on some devices, but have not been widely produced or distributed.

"Hospital systems, medical practitioners, and regulatory entities need to press for regulatory scrutiny and design equity by limiting purchasing choices to devices with equal performance for patients of all skin tones," the editorial writers say.

"In the meantime, a clinical strategy for avoiding under treating hypoxia in patients with darker skin is, unfortunately, lowering the threshold for suspected disease and obtaining more arterial blood gases," they add.

The study had no commercial funding and the authors have no relevant disclosures.

SOURCE: JAMA Internal Medicine, online May 31, 2022.