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Standard measure may underestimate OSA in Black patients



Measurement error may be the culprit in underdiagnosing obstructive sleep apnea in Black patients, compared with White patients, based on data from nearly 2,000 individuals.

Data collected from ICU patients during the COVID-19 pandemic suggested that pulse oximetry devices used to measure oxygen saturation may be less accurate for patients with darker skin, according to Ali Azarbarzin, PhD, of Harvard Medical School, Boston.

“We wanted to examine the implications for obstructive sleep apnea,” which is often caused by a reduction in air flow, Dr. Azarbarzin said in an interview.

In a study presented at the American Thoracic Society’s international conference, Dr. Azarbarzin and colleagues examined data from 1,955 adults who were enrolled in the Multi-Ethnic Study of Atherosclerosis (MESA) Exam 5. The study participants underwent unattended 15-channel polysomnography that included a finger pulse oximeter. The mean age of the participants was 68.3 years, and 53.7% were women. A total of 12.1%, 23.7%, 27.7%, and 36.5% of the participants were Asian, Hispanic, Black, and White, respectively.

Apnea hypopnea index (AHI3P) was similar between Black and White patients, at approximately 19 events per hour. Black participants had higher wake SpO2, higher current smoking rates, and higher body mass index, compared with White participants, but these differences were not significant.

Severity of obstructive sleep apnea (OSA) was based on the hypoxic burden, which was defined as the total area under the respiratory curve. The total ventilatory burden was defined as the event-specific area under the ventilation signal and identified by amplitude changes in the nasal pressure signal. The researchers then calculated desaturation sensitivity (the primary outcome) as hypoxic burden divided by ventilatory burden.

In an unadjusted analysis, desaturation sensitivity was significantly lower in Black patients and Asian patients, compared with White patients (P < .001 and P < .02, respectively). After adjusting for age, sex, body mass index, and time spent in a supine position, desaturation sensitivity was lower only in Black patients, compared with White patients, and this difference persisted in both men and women.

The difference in desaturation sensitivity by race could be caused by differences in physiology or in measurement error, Dr. Azarbarzin told this news organization. If measurement error is the culprit, “we may be underestimating OSA severity in [Black people],” especially in Black women, he said.

However, more research is needed to understand the potential impact of both physiology and device accuracy on differences in oxygen saturation across ethnicities and to effectively identify and treat OSA in all patients, Dr. Azarbarzin said.

The MESA Study was supported by the National Institutes of Health and the National Institute on Aging. Data from MESA were obtained through support from the National Heart, Lung, and Blood Institute and the National Center for Advancing Translational Sciences. Dr. Azarbarzin disclosed funding from the National Institutes of Health, the American Health Association, and the American Academy of Sleep Medicine.

A version of this article first appeared on

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