Two different definitions are used to score hypopneas toward an obstructive sleep apnea (OSA) diagnosis in the United States:
- a 30% airflow decrease with a 3% oxygen desaturation or EEG arousal, or
- a 30% airflow decrease with a 4% oxygen desaturation.
The Centers for Medicare and Medicaid Services and some 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,” says corresponding author Sanford Auerbach, MD, associate professor of neurology at the school and a sleep specialist at Boston Medical Center, in a release.
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.
