Prevalence of Sleep Apnea Syndrome in Japanese Patients with Persistent Fatigue

Background: Sleep apnea syndrome (SAS) is a common medical condition with significant adverse effects; however, it remains undiagnosed in many individuals. This study was conducted to assess the prevalence of SAS in fatigued subjects and to elucidate the factors associated with SAS. Methods: From March 2008 to March 2011, a cross-sectional, observational study was conducted in patients with persistent (>= 1 month) fatigue. Patients with known causes of persistent fatigue were excluded. Data on patient characteristics (e.g., blood pressure, neck circumference, etc.) and overnight pulse oximetry were collected. SAS was defined as a 3% oxygen desaturation index (ODI) of 15 or more. Results: Among 46 subjects, the prevalence of SAS was 6.5% (95% CI, 1.4-17.9%). SAS was significantly more prevalent in patients with high systolic blood pressure (>= 140 mmHg) than in patients with normal systolic blood pressure (<140 mmHg) (33.3% vs. 2.8%, P=0.049). Even after adjustment for age and sex, high systolic blood pressure showed a statistically significant association with SAS. Conclusions: Promoting awareness about SAS could be necessary in patients with persistent fatigue, especially in patients with high systolic blood pressure.