Morning and Evening Home Blood Pressure and Risks of Incident Stroke and Coronary Artery Disease in the Japanese General Practice Population: The Japan Morning Surge-Home Blood Pressure Study

Our aim is to determine the optimal time schedule for home blood pressure (BP) monitoring that best predicts stroke and coronary artery disease in general practice. The Japan Morning Surge-Home Blood Pressure (J-HOP) study is a nationwide practice-based study that included 4310 Japanese with a history of or risk factors for cardiovascular disease, or both (mean age, 65 years; 79% used antihypertensive medication). Home BP measures were taken twice daily (morning and evening) over 14 days at baseline. During a mean follow-up of 4 years (16 929 person-years), 74 stroke and 77 coronary artery disease events occurred. Morning systolic BP (SBP) improved the discrimination of incident stroke (C statistics, 0.802; 95% confidence interval, 0.692-0.911) beyond traditional risk factors including office SBP (0.756; 0.646-0.866), whereas the changes were smaller with evening SBP (0.764; 0.653-0.874). The addition of evening SBP to the model (including traditional risk factors plus morning SBP) significantly reduced the discrimination of incident stroke (C statistics difference, -0.008; 95% confidence interval: -0.015 to -0.008; P=0.03). The category-free net reclassification improvement (0.3606; 95% confidence interval, 0.1317-0.5896), absolute integrated discrimination improvement (0.015; SE, 0.005), and relative integrated discrimination improvement (58.3%; all P<0.01) with the addition of morning SBP to the model (including traditional risk factors) were greater than those with evening SBP and with combined morning and evening SBP. Neither morning nor evening SBP improved coronary artery disease risk prediction. Morning home SBP itself should be evaluated to ensure best stroke prediction in clinical practice, at least in Japan. This should be confirmed in the different ethnic groups.