Sex differences in the effectiveness and affecting factors to adherence of continuous positive airway pressure therapy.

Although sex differences in clinical backgrounds of patients with obstructive sleep apnea (OSA) are well known, studies of sex differences about the influencing factors on adherence to continuous positive airway pressure (CPAP) are very sparse. Our aim was to investigate the effects of CPAP use affecting therapeutic adherence in sex differences. We retrospectively assessed demographic data, clinical characteristics, OSA-related symptoms, and effects and adherence of CPAP use in 348 patients (264 males, median age 58 years) who continued CPAP for at least 1 year. Poor adherence was defined as CPAP dropout within 1 year after starting CPAP or the average cumulative CPAP use less than four hours/night. We also studied the predictors or influencing factors of CPAP adherence by multivariate logistic regression analyses. Age was higher and the severity of OSA was lower in female patients. Although the adherence level itself was not significantly different between both sexes, influencing factors were different. OSA severity, such as apnea-hypopnea index and sleepiness, and many effects from CPAP use (respiratory difficulty, difficult adaptation to CPAP use, improved awakening, reduced nocturia, and easy adaptation to CPAP) influenced adherence only in men. Common factors of poor adherence in both sexes were lower age, insomnia by CPAP use, and improved daytime sleepiness. No other specific factors predicted poor adherence in women. We found that there were sex differences in influencing factors on CPAP adherence not only in clinical characteristics of OSA, but also in effectiveness and side effects of CPAP use.