Nighttime Blood Pressure Measured by Home Blood Pressure Monitoring as an Independent Predictor of Cardiovascular Events in General Practice: The J-HOP Nocturnal Blood Pressure Study

We developed an innovative automated home blood pressure (BP) monitoring method that measures BP while asleep repeatedly over several days. Our aim was to assess the predictive ability of nighttime BP obtained using the home BP device for incident cardiovascular disease (CVD) in general practice patients. We used data from the nationwide practice-based J-HOP (Japan Morning Surge-Home Blood Pressure) Nocturnal BP Study, which recruited 2545 Japanese with a history of or risk factors for CVD (mean age 63 years; antihypertensive medication use 83%). The associations between nighttime home BPs (measured at 2:00, 3:00, and 4:00 am using validated, automatic, and oscillometric home BP devices) and incident CVD, including coronary disease and stroke events, were assessed with Cox proportional hazards models. The meanSD office, morning home, and nighttime home systolic BP (SBP)/diastolic BP were 140 +/- 15/82 +/- 10, 137 +/- 15/79 +/- 10, and 121 +/- 15/70 +/- 9 mmHg, respectively. During a follow-up of 7.1 +/- 3.8 years (18,116 person-years), 152 CVD events occurred. A 10-mmHg increase of nighttime home SBP was associated with an increased risk of CVD events (hazard ratios [95% CIs]: 1.201 [1.046-1.378]), after adjustments for covariates including office and morning home SBPs. The model fit assessed by the change in Goodness-of-Fit was improved when we added nighttime home SBP into the base models including office and morning home SBPs (6.838 [5.6%]; P=0.009). This is among the first and largest nationwide practice-based study demonstrating that nighttime SBP obtained using a home device is a predictor of incident CVD events, independent of in-office and morning in-home SBP measurement. Clinical Trial Registration URL: http://www.umin.ac.jp/icdr/index.html. Unique identifier: UMIN000000894.