Association of 24 h–systolic blood pressure variability and cardiovascular disease in patients with obstructive sleep apnea

BACKGROUND: To evaluate association of 24 h-systolic blood pressure (SBP) variability and obstructive sleep apnea (OSA) as defined by the apnea-hypopnea index ≥5/h; and association of 24 h-SBP variability and prevalent cardiovascular disease (CVD) in OSA patients. METHODS: Participants underwent polysomongraphy to evaluate the presence of OSA, and 24 h-ambulatory blood pressure monitoring was applied to evaluate 24 h-SBP variability as indexed by weighted 24 h-standard deviation (SD) of SBP. Between-group differences were evaluated in participants with and without OSA. Participants with OSA were divided into high and low 24 h-SBP variability groups and between-group differences were evaluated. RESULTS: Mean age of 384 participants was 50 years old and 42.2% had OSA. Mean 24 h-systolic/diastolic BP were 130/78 mmHg, with mean weighted 24 h-SD of systolic/diastolic BP were 12.9/7.3 mmHg. Compared to those without OSA, OSA participants had higher clinic-, 24 h-, daytime- and nighttime-SBP, and weighted 24 h, daytime- and nighttime-SD of SBP. Age, prevalent CVD and OSA, usage of angiotensin converting enzyme inhibitor/angiotensin receptor blocker, calcium channel blocker and diuretic were significantly associated with 24 h-SBP variability. In OSA patients, compared to those with low variability, participants with high variability had higher weighted 24 h, daytime- and nighttime-SD of SBP. After adjusted for covariates including clinic-SBP and 24 h-SBP, per 1-SD increment weighted 24 h-SD of SBP was associated with 21% increased prevalent CVD. CONCLUSIONS: Patients with newly-diagnosed OSA have higher 24 h-SBP variability compared to those without OSA; in OSA patients, increased 24 h-SBP variability is associated with increased prevalence of CVD.