Long-term effect of continuous positive airway pressure therapy on blood pressure in patients with obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common cause of hypertension. Previous studies have demonstrated beneficial short-term effects of continuous positive airway pressure (CPAP) therapy on blood pressure. However, long-term antihypertensive effects of CPAP have not been properly verified. This study examined the longitudinal effect of CPAP therapy adherence on blood pressure among OSA patients. All patients diagnosed with OSA and undergoing subsequent CPAP therapy at a Kanagawa-area sleep clinic were clinically followed for 24 months to examine CPAP adherence, as well as longitudinal changes in blood pressure and body weight because it may become a confound factor for changes in blood pressure. The hours of CPAP usage were collected over the course of 30 nights prior to each follow-up visit (1st, 3rd, 6th, 12th, and 24th month). The relationship between CPAP adherence and blood pressure was analyzed using mixed-effect logistic regression models. A total of 918 OSA patients were enrolled in the study. We found a significant reduction in diastolic blood pressure among patients with good CPAP adherence during the 24-month follow-up period (β = − 0.13, p = 0.03), when compared to the group with poor CPAP adherence. No significant association was found between CPAP adherence and weight loss (β = − 0.02, p = 0.59). Long-term, good CPAP therapy adherence was associated with lower diastolic blood pressure without significant weight loss.