Association of Night‐to‐Night Adherence of Continuous Positive Airway Pressure With Day‐to‐Day Morning Home Blood Pressure and Its Seasonal Variation in Obstructive Sleep Apnea

BACKGROUND: The aim of this study was to investigate the association between night‐to‐night adherence to continuous positive airway pressure (CPAP) therapy and both home blood pressure (BP) level on the following day and seasonal variation in home BP in patients with obstructive sleep apnea. METHODS AND RESULTS: We analyzed 105 participants who had been diagnosed with obstructive sleep apnea (average apnea‐hypopnea index, 49.7±18.4 per hour) and who were already receiving CPAP therapy. Home BP (twice every morning and evening) and CPAP adherence data were automatically transmitted to a server for 1 year. A mixed‐effects model for repeated measures analysis was used to examine associations of night‐to‐night good CPAP adherence with day‐to‐day home BP within the same patient after adjusting for covariates. The average number of days in which patients achieved both CPAP adherence and morning or evening home BP measurement was 206.6±122.7 days (21 487 readings) and 191.2±126.3 days (20 170 readings), respectively. Good CPAP adherence (>4 hours per night of use) was achieved on the evening or morning before home BP measurements (86.8% and 86.9%, respectively). After adjustment for confounders, good CPAP adherence was negatively associated with morning home systolic BP (β, −0.663; P=0.004) and diastolic BP (β, −0.829; P<0.001). Morning home systolic BP in winter in the individuals with good CPAP adherence was significantly lower than that in individuals without such adherence (P<0.05). These associations were not found in evening home BP. CONCLUSIONS: Good adherence to CPAP therapy was negatively associated with morning home BP on the following day in patients with obstructive sleep apnea. The association was remarkable in the winter season.