Pulse oximeters may misjudge sleep apnea severity in Black patients
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Key takeaways:
- Black vs. white patients showed reduced desaturation sensitivity following adjustment for confounders.
- This result was not found in Asian or Hispanic patients when compared with white patients.
WASHINGTON — Black patients had decreased desaturation sensitivity during sleep recorded by pulse oximeters, according to research presented at the American Thoracic Society International Conference.
“Our findings suggest that these measurement problems may lead to underestimation of the severity of OSA in Black individuals,” Ali Azarbarzin, PhD, assistant professor of medicine at Harvard Medical School, said in an ATS press release. “However, whether this underestimation of oxygen drops should lead to important differences in diagnosing and managing OSA in Black and other individuals with dark skin is unclear.”
Azarbarzin and colleagues evaluated 1,955 patients (mean age, 68.3 years; 53.7% women) who participated in the Multi-Ethnic Study of Atherosclerosis (MESA) Exam 5 to observe differences in desaturation sensitivity during sleep measured through a finger pulse oximeter between patients of different races/ethnicities.
Of the total cohort of patients who participated in 15-channel polysomnography (Somté PSG, Compumedics Ltd., Abbotsford, Australia), 36.5% were white, 27.7% were Black, 23.7% were Hispanic and 12.1% were Asian.
Using measures of hypoxic burden (“total area under respiratory event-related desaturation curves”) and ventilatory burden (“event-specific area under the ventilation signal”), researchers found desaturation sensitivity by dividing the two datapoints, according to the abstract.
When comparing sleep desaturation based on a patient’s race/ethnicity, researchers adjusted for various confounders, including age, sex, BMI, smoking and percent time in supine position in multiple linear regression models.
In terms of baseline characteristics, more Black patients reported current smoking than white patients (11.8% vs. 5.9%). Black patients also had increased wake SpO2 (96.1% vs. 95.7%) and BMI (30.4 kg/m2 vs. 27.9 kg/m2) compared with white patients. According to the abstract, apnea-hypopnea index was comparable between white patients (18.7 events per hour) and Black patients (19.4 events per hour).
Prior to adjusting for confounding variables, researchers found that both Asian patients and Black patients had lower desaturation sensitivity than white patients by 0.31 standard deviation (SD; P < .001) and 0.13 SD (P = .02), respectively.
Unlike Asian or Hispanic patients, Black patients showed reduced desaturation sensitivity following adjustment for the outlined confounders compared with white patients, with a 0.27 SD (P < .001) lower measure.
When observing differences among races/ethnicities after adjusting for baseline saturation, researchers again found that Black patients had lower desaturation severity. This outcome was further found after stratifying patients by sex, according to the abstract.
“These findings highlight the need to rigorously test the accuracy of oximeters across diverse populations and also to consider whether factors other than the oximeter’s characteristics could explain differences in oxygen patterns with breathing pauses,” Azarbarzin said in the release.
Reference:
- The severity of sleep apnea may be underestimated in Black patients. https://www.thoracic.org/about/newsroom/press-releases/conference/resources/racial-differences-and-sleep-apnea.pdf. Published May 15, 2023. Accessed May 23, 2023.
Perspective
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This study is interesting in that it suggests that our current “gold standard” for assessing sleep apnea might underrepresent the degree of sleep apnea in Black patients due to race-based differences in oxygen desaturation from respiratory events. It is unclear whether these findings are clinically significant. A reanalysis of the data or further research is needed to determine if this difference actually led to significantly fewer Black people being diagnosed with sleep apnea or presenting as a milder degree of sleep apnea than subjects of other races. This research is a bit surprising because previous evidence has suggested that Black individuals have a higher incidence of sleep apnea than white individuals. Physicians might consider being more vigilant in treating mild sleep apnea in the Black population.
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