Racial and Ethnic Bias in Pulse Oximetry and Clinical Outcomes

Abstract

Assessment of blood oxygen saturation is an important measure of health on which many diagnostic and treatment decisions are based. Blood oxygen saturation is most commonly assessed via pulse oximetry, with increasing use across the home, clinic, and hospital settings during the COVID-19 pandemic. 1 However, inaccuracies in pulse oximetry measurement have come under scientific scrutiny over the past 2 years. [2][3][4][5][6] Professional organizations, lawmakers, and the public have actively engaged with the issue. 4 A known design flaw of the pulse oximeter is that patients with darker skin (compared with lighter skin) are more likely to experience occult hypoxemia-defined conceptually as substantial arterial hypoxemia (SaO 2 ) detected on blood gas but not noted on simultaneous pulse oximetry (SpO 2 ). 1 Less is known about whether underdiagnosis of hypoxemia for historically marginalized racial and ethnic groups has consequences.In their article "Racial and Ethnic Discrepancy in Pulse Oximetry and Delayed Identification of Treatment Eligibility Among Patients With COVID-19," Dr Fawzy and colleagues evaluate this measurement bias in pulse oximetry among a population of hospitalized patients diagnosed with COVID-19. 7 The authors show measurement bias was associated with differences in delay in recognizing patients' eligibility for COVID-19 treatment, with racial and ethnic minoritized groups being more affected. Although less visible, this is similar to the ways in which race-and ethnicity-based cutoffs in pulmonary function tests and estimated glomerular filtration fraction 8 lead to underestimation of disease severity among patients of racial and ethnic minoritized groups, which in turn delays treatment of severe lung disease and limits access to timely kidney replacement therapy, including transplantation.The study by Dr Fawzy and colleagues was a retrospective analysis using a large database from 5 well-resourced hospitals. 7 As in other investigations of pulse oximetry, the authors evaluated clinical SaO 2 and SpO 2 measurements within 10 minutes of each other, a design that allows for head-tohead comparison of pulse oximetry estimations of arterial oxygenation with the gold standard from blood gas analysis. Using race and ethnicity as a proxy for skin color, the authors chose to aggregate the data for Black−Hispanic patients and Black patients into a single study group.Dr Fawzy and colleagues reported higher rates of occult hypoxemia (SaO 2 <88% when SpO 2 was 92%-96%) for Asian, Black, and Hispanic patients compared with non-Hispanic White patients, as well as delayed or unrecognized eligibility for the US Centers for Disease Control and Prevention guidelineconcordant COVID-19 treatments (eg, steroids, remdesivir) for

Racial bias and reproducibility in pulse oximetry among medical and surgical inpatients in general care in the Veterans Health Administration 2013-19: multicenter, retrospective cohort study

“…Large integrated health systems such as the Veterans Health Administration and NHS could have a role to purchase and use only pulse oximeters proven to provide equivalent accuracy in black patients rather than devices of unproven equity. 33 34 …”

Low perfusion and missed diagnosis of hypoxemia by pulse oximetry in darkly pigmented skin: A prospective study

“…In this prospective study of healthy volunteers, we have found that low perfusion interacts with both medium and dark skin pigment to substantially increase pulse oximeter bias. For subjects with dark skin and low perfusion, these errors lead to missed hypoxemia diagnoses at frequencies comparable to or higher than those reported for Black hospitalized patients in retrospective clinical studies 9-12 . Because critical illness is commonly associated with low peripheral perfusion, this finding may be of significant clinical importance.…”

“…For subjects with dark skin and low perfusion, these errors lead to missed hypoxemia diagnoses at frequencies comparable to or higher than those reported for Black hospitalized patients in retrospective clinical studies [9][10][11][12] . Because critical illness is commonly associated with low peripheral perfusion, this finding may be of significant clinical importance.…”

“…Due to the vasodilatory actions of anesthetics and use of forced air warming in the operating room, peripheral perfusion in surgical patients is expected to be greater than in other hospitalized patients. Therefore, we are not surprised that the incidence reported by Burnett of missed diagnosis of hypoxemia in black patients is about half that in non-surgical patient cohorts reported by Sjoding, Valbuena, and others [9][10][11][12] .…”

“…However, there is growing concern and evidence to suggest that current healthy human, laboratory-based study validation protocols may not adequately predict performance in real-world clinical settings 8 . Recent retrospective studies report missed diagnoses of hypoxemia in patients with darkly pigmented skin at twice the rate compared to White patients [9][10][11][12] . These findings have prompted inquiries by multiple regulatory bodies worldwide, including letters from Congress to the FDA and a new FDA communication 13,14 .…”