Gender differences in the clinical characteristics among Japanese patients with obstructive sleep apnea syndrome

Gender differences in the prevalence of various manifestations of obstructive sleep apnea syndrome (OSAS) is not as great as previously believed. The aim of the present study was to clarify the clinical patient characteristics of Japanese women and men with OSAS.

A cross-sectional case-match control study was performed on patients from two sleep disorder centers. Two hundred forty-five women with OSAS were classified into premenopausal (n = 70) and postmenopausal (n = 175) groups. As well, 245 men matched for both age and apnea-hypopnea index (AHI) and another 245 men matched for age and body mass index (BMI) were established. We compared descriptive variables between genders in both the premenopausal and the postmenopausal female patient groups.

As a whole, female patients had significantly higher BMI than AHI-matched male patients (p < 0.05) and a significantly lower value of AHI than BMI-matched male patients (p < 0.001). Female patients had lower Epworth Sleepiness Scale scores than BMI-matched male patients (p < 0.05). On logistic regression analysis, presence of hypertension was significantly associated with BMI (>or=25 kg/m(2)), AHI (>or= 15 to < 30 events/h; >or= 30 to < 60 events/h; >or= 60 events/h), and presence of both hyperlipidemia and diabetes mellitus. However, gender differences were not associated with the occurrence of hypertension. Female patients had significantly lower optimal levels of continuous positive airway pressure than male patients.

Our results suggest that both the OSAS severity and the strength of pharyngeal closure is less in Japanese female patients than in male patients. Moreover, Japanese female patients are thought to have less daytime sleepiness than male patients but a similar rate of hypertension as male patients.