Clinical Outcomes Associated With Overestimation of Oxygen Saturation by Pulse Oximetry in Patients Hospitalized With COVID-19

Abstract

ImportanceMany pulse oximeters have been shown to overestimate oxygen saturation in persons of color, and this phenomenon has potential clinical implications. The relationship between overestimation of oxygen saturation with timing of COVID-19 medication delivery and clinical outcomes remains unknown.ObjectiveTo investigate the association between overestimation of oxygen saturation by pulse oximetry and delay in administration of COVID-19 therapy, hospital length of stay, risk of hospital readmission, and in-hospital mortality.Design, Setting, and ParticipantsThis cohort study included patients hospitalized for COVID-19 at 186 acute care facilities in the US with at least 1 functional arterial oxygen saturation (SaO2) measurement between March 2020 and October 2021. A subset of patients were admitted after July 1, 2020, without immediate need for COVID-19 therapy based on pulse oximeter saturation (SpO2 levels of 94% or higher without supplemental oxygen).ExposuresSelf-reported race and ethnicity, difference between concurrent SaO2 and pulse oximeter saturation (SpO2) within 10 minutes, and initially unrecognized need for COVID-19 therapy (first SaO2 reading below 94% despite SpO2 levels of 94% or above).Main Outcome and MeasuresThe association of race and ethnicity with degree of pulse oximeter measurement error (SpO2 − SaO2) and odds of unrecognized need for COVID-19 therapy were determined using linear mixed-effects models. Associations of initially unrecognized need for treatment with time to receipt of therapy (remdesivir or dexamethasone), in-hospital mortality, 30-day hospital readmission, and length of stay were evaluated using mixed-effects models. All models accounted for demographics, clinical characteristics, and hospital site. Effect modification by race and ethnicity was evaluated using interaction terms.ResultsAmong 24 504 patients with concurrent SpO2 and SaO2 measurements (mean [SD] age, 63.9 [15.8] years; 10 263 female [41.9%]; 3922 Black [16.0%], 7895 Hispanic [32.2%], 2554 Asian, Native American or Alaskan Native, Hawaiian or Pacific Islander, or another race or ethnicity [10.4%], and 10 133 White [41.4%]), pulse oximetry overestimated SaO2 for Black (adjusted mean difference, 0.93 [95% CI, 0.74-1.12] percentage points), Hispanic (0.49 [95% CI, 0.34-0.63] percentage points), and other (0.53 [95% CI, 0.35-0.72] percentage points) patients compared with White patients. In a subset of 8635 patients with a concurrent SpO2 − SaO2 pair without immediate need for COVID-19 therapy, Black patients were significantly more likely to have pulse oximetry values that masked an indication for COVID-19 therapy compared with White patients (adjusted odds ratio [aOR], 1.65; 95% CI, 1.33-2.03). Patients with an unrecognized need for COVID-19 therapy were 10% less likely to receive COVID-19 therapy (adjusted hazard ratio, 0.90; 95% CI, 0.83-0.97) and higher odds of readmission (aOR, 2.41; 95% CI, 1.39-4.18) regardless of race (P for interaction = .45 and P = .14, respectively). There was no association of unrecognized need for COVID-19 therapy with in-hospital mortality (aOR, 0.84; 95% CI, 0.71-1.01) or length of stay (mean difference, −1.4 days; 95% CI, −3.1 to 0.2 days).Conclusions and RelevanceIn this cohort study, overestimation of oxygen saturation by pulse oximetry led to delayed delivery of COVID-19 therapy and higher probability of readmission regardless of race. Black patients were more likely to have unrecognized need for therapy with potential implications for population-level health disparities.

Skin Pigmentation and Pulse Oximeter Accuracy in the Intensive Care Unit: a Pilot Prospective Study

“…Most recent studies investigating the impact of skin pigmentation on pulse oximeter accuracy among adults in clinical settings have substituted race and ethnicity for objective skin tone measurements. (9)(10)(11)(12)(13)(14)(15)(21)(22)(23) Laboratory studies of healthy volunteers that subjectively evaluated skin pigmentation have reported poor accuracy at low saturations (<80%) among darkly pigmented individuals compared with lighter pigmented individuals. (7,8) However, a reanalysis of proprietary healthy volunteer laboratory data reported no difference in pulse oximeter accuracy between Black and White volunteers.…”

“…(9)(10)(11)(12) Unrecognized hypoxemia is associated with delay in delivering COVID-19 therapy and higher readmission rate among COVID-19-infected patients. (13,14) However, past clinical studies have major limitations. First, race and ethnicity as recorded in the electronic medical record (EMR) was used as a surrogate for skin pigmentation, the presumed relevant physiologic parameter.…”

Tissue mimicking materials and finger phantom design for pulse oximetry

“…For example, a retrospective study on 7126 patients with COVID-19 with a total of 32,282 concurrently measured SpO 2 and oxygen saturation levels in arterial blood (SaO 2 ) showed that SpO 2 values of self-identified Asian, Black, and Hispanic patients were overestimated and higher than SaO 2 by an average of 1.33% when compared to White patients, which led physicians to administer lower levels of oxygen [ 5 ]. In a follow-up study, researchers confirmed that skin tone can lead to delayed care as pulse oximeters may provide inaccurate readings in individuals of ethnicities that are known to have a higher prevalence of darker skin, affecting the timely administration of necessary treatments [ 6 ]. Moreover, researchers found that SpO 2 overestimation increased the risk of hospital readmission regardless of patient race, emphasizing the importance of accurate monitoring.…”

Pulse Oximetry Misclassifies Need for Long-Term Oxygen Therapy in Chronic Obstructive Pulmonary Disease

“…For instance, pulse oximetry has become ubiquitous in the acute care setting despite evidence at the turn of the 21st century of the poor performance of pulse oximeters in this context ( 11 ). Likewise, warnings that pulse oximeters were less accurate in individuals with darker pigmentation went unheeded for decades by the medical community and regulators until investigations spurred by the coronavirus disease (COVID-19) pandemic highlighted the tendency of pulse oximeters to overestimate true oxygen saturation among individuals of racial and ethnic minorities and the adverse clinical consequences of this health disparity ( 12 – 16 ). In addition to evaluating the misclassification of the need for supplemental oxygen, Garnet and colleagues evaluated the risk factors for inaccurate estimation of arterial oxygen saturation by pulse oximetry.…”