Pulse Oximetry Overestimation of O₂ Saturation Caused Delayed COVID-19 Therapy

Overestimation of O₂ saturation based on pulse oximetry, which happened more often in Black patients, led to COVID-19 therapy delays and readmissions regardless of race/ethnicity, according to study findings published in JAMA Network Open.

Research has shown that pulse oximetry, a light-based technology, often overestimates oxygen saturation in persons of color. Researchers sought to determine the association between overestimation of oxygen saturation by pulse oximetry with delayed administration of COVID-19 therapy, hospital length of stay, risk of hospital readmission, and in-hospital mortality, using data from the COVID-19 Consortium of HCA Healthcare and Academia for Research Generation (CHARGE). The database includes electronic health records of patients hospitalized for COVID-19 between March 1, 2020, and October 31, 2021, in 186 HCA Healthcare acute-care facilities in the US.

The participants had at least 1 functional arterial oxygen saturation (SaO₂) measurement during hospitalization. For each SaO₂ value, the nearest estimated oxygen saturation by pulse oximetry (SpO₂) was identified within 10 minutes of arterial blood sample acquisition. The degree of error in the estimation of oxygen saturation by pulse oximetry was the difference between SpO₂ and SaO₂.

A total of 40,738 patients with at least 1 SaO₂ measure were identified, of whom 24,504 patients (41.9% female, 16.0% Black, 32.2% Hispanic, 10.4% other race or ethnicity, and 41.4% White) had 213,229 SaO₂ records paired to a SpO₂ result within 10 minutes.

After adjustment, SpO₂ significantly overestimated SaO₂ by 0.93 (95% CI, 0.74-1.12) percentage points in Black patients, by 0.49 (95% CI, 0.34-0.63) percentage points in Hispanic patients, and by 0.53 (95% CI, 0.36-0.72) percentage points in patients from other racial or ethnic minority groups vs White patients.

Among patients with a visit date after July 1, 2020, and admission SpO₂ of at least 94% in the absence of supplemental oxygen, 8635 (54.1%) had at least 1 concurrent SpO₂ − SaO₂ pair. Black and Hispanic patients were significantly more likely to have an unrecognized need for COVID-19 therapy by oxygen saturation (SpO₂ ≥94% despite having SaO₂ levels <94%). Black patients had a higher effect size (adjusted odds ratio [aOR], 1.46; 95% CI, 1.23-1.72) vs Hispanic patients (aOR, 1.18; 95% CI, 1.01-1.39); the difference was not significant in patients of other races/ethnicities (aOR, 1.23; 95% CI, 1.00-1.52).

Participants with an initially unrecognized need for COVID-19 therapy according to pulse oximetry error received treatment a median of 7.3 hours (interquartile range [IQR], 2.8-23.4 hours) vs 6.5 hours (IQR, 2.0-21.3) in those with a recognized need for therapy and had a 10% lower hazard of receiving COVID-19 therapy (adjusted hazard ratio [aHR], 0.90; 95% CI, 0.83-0.97). These patients also had a significantly increased odds of readmission (aOR, 2.41; 95% CI, 1.39-4.18).

Participants who had an unrecognized need for COVID-19 treatment had point estimates of lower in-hospital mortality (aOR, 0.84; 95% CI, 0.71-1.01) as well as a shorter length of stay (mean difference, -1.4 days; 95% CI, -3.1 to 0.2 days), although neither was statistically significant.

Among several limitations, some patients could have initiated oxygen therapy due to dyspnea regardless of oxygen saturation and would have been excluded, and the findings may not be generalizable to a broad population of individuals with COVID-19. Also, time to treatment administration may have been affected by several unmeasured variables, and the population did not include an adequate sample size of patients from racial and ethnic groups other than Black, Hispanic, and White.

[O]verestimation of oxygen saturation by pulse oximetry led to delayed delivery of COVID-19 therapy and higher probability of readmission regardless of race,” said the study authors. “Black patients were more likely to have unrecognized need for therapy with potential implications for population-level health disparities,” they added.

Disclosure: Some of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.