Pulse Oximeters May Undercount Sleep Apnea Severity in Black Patients

Pulse Oximeters Undercount Obstructive Sleep Apnea Severity in Black Patients

The Tech TL;DR:

• New clinical data published in 2026 reveals pulse oximeters may undercount breathing events, with the proportion of airflow-defined events meeting the standard oxygen-desaturation criterion roughly 20 percent lower in Black patients.
• Researchers analyzed two independent cohorts, MESA and SHHS, comparing oxygen-desaturation metrics against independent airflow and heart-rate measures.
• The findings indicate that standard oxygen-based scoring may fail to register clinically relevant events because of light absorption characteristics of darker skin pigmentation.

Diagnostic tools used in sleep laboratories routinely rely on blood oxygen measurements to gauge the severity of obstructive sleep apnea. Investigators from Mass General Brigham reported in the American Journal of Respiratory and Critical Care Medicine that this reliance on pulse oximetry may introduce a racial bias. Specifically, the proportion of airflow-defined breathing events meeting standard oxygen-desaturation criteria was roughly 20 percent lower in Black participants compared to white participants across two separate study populations.

Two Independent Cohorts Reveal Consistent Scoring Disparities

To evaluate whether skin pigmentation interferes with apnea scoring, researchers analyzed data from the Multi-Ethnic Study of Atherosclerosis (MESA) and the Sleep Heart Health Study (SHHS). Pulse oximeters function by emitting light through tissue and measuring light absorption. Melanin and other pigments in darker skin absorb portions of this emitted light, which can skew output readings. While this clinical bias has been documented in other medical settings—including during evaluations for Covid-19 infections—its precise impact on obstructive sleep apnea diagnosis remained unmeasured until now.

The research team compared severity scores derived from blood oxygen desaturation against two alternative metrics that do not depend on oxygen saturation: direct airflow measurements and heart-rate responses. Across the MESA dataset, the proportion of airflow-defined events meeting the standard 4 percent oxygen-desaturation threshold was 21 percent lower in Black participants than in white participants. In the SHHS cohort, the discrepancy held at 20 percent. When conventional oxygen-based scoring rules were applied, a substantial fraction of identical breathing disturbances simply failed to register in Black individuals.

Heart-Rate Metrics Highlight the Hidden Breathing Events

To confirm whether the disparity stemmed from actual physiological differences or algorithmic artifacts, investigators tracked alternative physiological indicators. Heart-rate-based scoring showed no comparable racial gap between the cohorts. If Black participants had experienced genuinely milder or fewer apnea events, a scoring system tracking autonomic heart-rate responses would have captured a similar reduction. It did not. The heart-rate-based severity measure was associated with cardiovascular events and death in Black participants across both cohorts, whereas the standard oxygen-based severity measures showed no significant association with those long-term outcomes.

“Our findings raise concern that pulse oximetry–based sleep apnea scoring may under detect clinically relevant events in some Black individuals, with potential implications for diagnosis and severity classification.”

noted first author Ali Azarbarzin, PhD, of the Division of Sleep and Circadian Disorders in the Department of Medicine at Mass General Brigham. Azarbarzin clarified the intent of the work: We are not suggesting different diagnostic thresholds based on race; rather, we think the underlying measurements need to be accurate and reliable across all patients.

Obstructive sleep apnea severity scores directly drive clinical decisions regarding patient referrals, diagnostic staging, and treatment pathways. When standard oxygen-based algorithms miss critical breathing disturbances, affected individuals may appear less severe on paper than their underlying physiology warrants.