Pulse Oximetry Inaccuracies Delayed COVID-19 Treatment

Overestimation of oxygen saturation by pulse oximetry led to delayed delivery of COVID-19 therapy, and an unrecognized need for therapy among Black patients, according to a retrospective cohort study.

Among over 24,000 patients with concurrent pulse oximeter saturation (SpO₂) and arterial oxygen saturation (SaO₂) measurements, those with an initially unrecognized need for COVID therapy were 10% less likely to receive therapy (adjusted HR 0.90, 95% CI 0.83-0.97), regardless of race (P=0.45 for interaction), reported Tianshi David Wu, MD, MHS, of Baylor College of Medicine in Houston, and co-authors.

These patients also had higher odds of readmission (adjusted OR 2.41, 95% CI 1.39-4.18), with race again not playing a role (P=0.14 for interaction), they noted in JAMA Network Open.

However, looking at a subset of 8,635 patients who didn’t have an immediate need for COVID therapy, Black patients were significantly more likely to have pulse oximetry values that did not indicate a need for COVID therapy compared with white patients (adjusted OR 1.65, 95% CI 1.33-2.03).

“Taken together, these findings paint a complementary picture of the impact of pulse oximeter inaccuracy in clinical decision-making and patient outcomes,” the authors wrote.

“Variability in the accuracy of pulse oximeters has been previously reported, and the impact it has shown in patients of all races emphasizes the multifactorial nature of pulse oximeter accuracy, extending beyond skin pigmentation,” they noted.

A study from earlier this year also showed pulse oximetry overestimated SaO₂ in Black children compared with white children.

Of note, in this study, patients who had an initially unrecognized need for COVID therapy based on pulse oximetry error received treatment at a median of 7.3 hours compared with 6.5 hours for those whose need for therapy was recognized right away.

“While this inaccuracy was more likely to happen for Black patients, both Black and white patients who had this inaccuracy saw similar delays in receiving COVID-19 medication,” Wu told MedPage Today in an email. “This suggests that racial bias in pulse oximeter accuracy is a key factor for the treatment differences between Black and white patients in our data.”

“Clinically, our results again emphasize that physicians should scrutinize ‘borderline’ values reported by the pulse oximeter and not hinge important medical decisions on such numbers,” he added.

William Padula, PhD, of the University of Southern California in Los Angeles, told MedPage Today that while pulse oximeters may have performed well in some previous trials, patient samples may not have been as representative of current populations.

“I think what we’ve learned as a society, especially as we prioritize health equity with respect to other priorities and healthcare delivery, is that the number of patients sampled in calibration of these pulse oximeters were not from underrepresented minority groups, specifically to this paper, individuals with darker skin tones,” he said.

These findings “are showing, through health outcomes as a result of health technology that showed efficacy in clinical trials, once you put it in the real world and expose it to the variability in real patient populations, you see that it doesn’t serve everybody equally,” he continued.

Padula encouraged the use of multiple diagnostic tools in order to ensure accurate diagnosis and more equitable care.

“I always say that sensory technology is amazing, it’s made healthcare more efficient. It’s ensured that we’re giving the right care for the right patient on a more regular basis,” he said, noting, however, that “health systems need to allocate more resources in order to ensure that, in addition to the technology, other data points are being collected for all individuals presenting with a concerning condition acutely, like COVID-19.”

For this study, Wu and colleagues used data from the COVID-19 Consortium of HCA Healthcare and Academia for Research Generation on 24,504 patients hospitalized for COVID at 186 acute care facilities in the U.S. with at least one functional SaO₂ measurement from March 2020 through October 2021.

Mean age was 63.9, 41.9% were women, 41.4% were white, 32.2% were Hispanic, 16% were Black, and 10.4% were categorized as Asian, Native American or Alaskan Native, Hawaiian or Pacific Islander, or another race or ethnicity. On average, patients from minority racial and ethnic groups were younger than white patients.

SaO₂ was overestimated by pulse oximetry in Black and Hispanic patients, as well as those of other racial identities, compared with white patients:

• Black: adjusted mean difference 0.93 percentage points (95% CI 0.74-1.12)
• Hispanic: adjusted mean difference 0.49 percentage points (95% CI 0.34-0.63)
• Other: adjusted mean difference 0.53 percentage points (95% CI 0.35-0.72)

The researchers acknowledged that other factors, such as hospital staffing, therapy availability, and practice patterns may have also affected time to treatment administration. Exclusion of patients receiving oxygen therapy as a result of dyspnea, potential deviation from established guidelines at provider locations, and the use of self-reported race and ethnicity as a substitute for actual skin tone, which can be varied, may have also limited the study findings, they noted.

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