Significant Correlates of Nocturnal Hypertension in Patients With Hypertension Who Are Treated With Antihypertensive Drugs

BACKGROUND: Nocturnal hypertension assessed by a home blood pressure monitoring (HBPM) device is associated with an increased risk of cardiovascular events. However, it is still difficult to assess nighttime blood pressure (BP) frequently. The purpose of this cross-sectional study was to identify significant correlates of nocturnal hypertension assessed by an HBPM device in patients with hypertension who are treated with antihypertensive drugs. METHODS: We measured nighttime BP, morning BP, and evening BP by an HBPM device for 7 consecutive days in 365 medicated patients with hypertension. RESULTS: Of the 365 subjects, 138 (37.8%) had nocturnal hypertension defined as a mean nighttime systolic BP of ≥ 120 mm Hg. Receiver operating characteristic curve analyses showed that the diagnostic accuracy of morning systolic BP for subjects with nocturnal hypertension was significantly superior to that of evening systolic BP (P = 0.04) and that of office systolic BP (P < 0.001). Multivariate analysis revealed that morning systolic BP of 125-<135 mm Hg (odds ratio [OR], 2.26; 95% confidence interval [CI], 1.13-4.58; P = 0.02), morning systolic BP of ≥ 135 mm Hg (OR, 16.4; 95% CI, 8.20-32.7; P < 0.001), and a history of cerebrovascular disease (OR, 3.99; 95% CI, 1.75-9.13; P = 0.001) were significantly associated with a higher risk of nocturnal hypertension and that bedtime dosing of antihypertensive drugs was significantly associated with a lower risk of nocturnal hypertension (OR, 0.56; 95% CI, 0.32-0.97; P = 0.04). CONCLUSIONS: Morning systolic BP of ≥ 125 mm Hg, a history of cerebrovascular disease, and bedtime dosing were significant correlates of nocturnal hypertension in medicated patients with hypertension, and may help detect this risky BP condition. CLINICAL TRIALS REGISTRATION: University Hospital Medical Information Network Clinical Trials Registry (UMIN000019173).