(Boston)—Obstructive sleep apnea (OSA) is a common sleep disorder in the U.S. affecting tens of millions, with estimates ranging from 25 to more than 80 million adults. However, most remain unaware they have the condition, which can cause severe health risks like high blood pressure, heart disease and impaired daytime function. OSA is often diagnosed using pulse oximetry, a non-invasive method for monitoring blood oxygen saturation. However prior studies have shown that pulse oximeters have the potential to overestimate oxygen saturation, and these instruments miss episodes of hypoxia at a greater rate in people with darker skin, particularly Black, Hispanic and Asian individuals, when compared to white individuals.
Two definitions are currently used by the American Academy of Sleep Medicine to determine OSA: a 30% airflow decrease with a 3% oxygen desaturation or EEG arousal (abrupt shift in brainwave frequency) or a 30% airflow decrease with a 4% oxygen desaturation. The Centers for Medicare and Medicaid Services and many commercial payers use only the 4% rule to confirm OSA, which may limit patient access to sleep apnea treatment.
A new study by researchers at Boston University Chobanian & Avedisian School of Medicine has found that despite known limitations of pulse oximetry associated with skin tone, no racial differences in the diagnosis of OSA were seen in this group. However, female patients had lower odds of meeting the 4% threshold, suggesting a potential barrier to treatment for women.
"While the use of the 4% rule compared to the 3% leads to a significant number of patients being excluded from OSA treatment, reassuringly, this does not appear to discriminate by race in our cohort. Female patients, on the other hand, are likely disadvantaged by the 4% rule," explained corresponding author Sanford Auerbach, MD, associate professor of neurology at the school and a sleep specialist at Boston Medical Center.
The researchers reviewed the medical records from 1,354 adults who underwent overnight sleep studies at an urban academic hospital. Medical history, demographics and comorbidities (age, sex, body mass index, anxiety, depression, hypertension, COPD and smoking) were collected and analyzed.
The researchers believe further work must be done to improve pulse oximetry to ensure the tools used to diagnose OSA are effective in all patient populations, as well as retiring the 4% rule in favor of the 3% rule to increase access to treatment and ensure equitable healthcare.
These findings appear online in the Journal of Clinical Medicine.
