Prognostic value of ambulatory and home blood pressure measurements in comparison to screening blood pressure measurements: A pilot study in Ohasama

Objective We investigated the risk for cardiovascular mortality according to blood pressure levels determined by screening, ambulatory and home blood pressure measurements. Methods A long-term prospective study of cardiovascular mortality has been conducted in Ohasama, Japan, since 1987. The relative hazard for cardiovascular mortality obtained by the Cox proportional hazard model (where age, sex and the use of antihypertensive medication were adjusted) was compared for screening blood pressure and home blood pressure measurements in 1789 subjects ≥40 years of age (mean follow-up 5.1 ± 2.2 years). Similarly the relative hazard was compared with screening blood pressure and ambulatory blood pressure in 1332 subjects ≥40 years of age (mean follow-up 4.7 ± 2.0 years). Results The relative hazard was significantly increased at the highest quintile of ambulatory systolic blood pressure (≥133 mmHg; relative hazard = 5.53; 95% confidence interval 1.26-24.26; P<0.02). The relative hazard tended to be increased in the lowest quintile. The same pattern was also observed for home systolic blood pressure (the highest quintile ≥138 mmHg; relative hazard = 5.74; 95% confidence interval 1.33-24.90; P<0.02) and home diastolic blood pressure (the highest quintile: ≥83 mmHg; relative hazard = 3.17; 95% confidence interval 1.15-8.71; P<0.03), and the relative hazard tended to be increased in the lowest quintile. Conclusion We observed a J-shaped relationship between baseline ambulatory or home blood pressure measurements and cardiovascular mortality during a 5-year follow-up period. This trend was not observed for the screening blood pressure. Our findings suggest that ambulatory and home blood pressure measurements have more reliable prognostic value than screening blood pressure measurements.