Ambulatory blood pressure normality: Experience in the Ohasama study

Objective: To define the reference values of ambulatory blood pressure (ABP) using results from the Ohasama study. Results: The distribution criteria of 24 h ABP for the total population of Ohasama were 135/79 (mean + SD), 148/86 (mean + 2 SD), and 146/85 mmHg (95th percentile), and those for normotensive subjects were 129/76 (mean + SD), 142/85 (mean + 2 SD) and 139/81 mmHg (95th percentile). The corresponding criteria [i.e. the 24 h ABP corresponding to 140/90 and 160/95 mmHg casual (clinical) blood pressure of the total population] were 125/76 and 132/76 mmHg. A long-term prospective study based on cardiovascular morbidity and mortality would provide the most meaningful values. For the prognostic criteria, based on nonparametric analysis, the hypertensive range of the 24 h ABP was postulated to be ≥ 134/≥ 78 mmHg, whereas that based on parametric analysis was postulated to be ≥ 134/≥ 79 mmHg. The lowest relative hazard was observed at 128/74 mmHg in parametric analysis. Thus, we tentatively propose reference values ≥ 135/≥ 80 mmHg for hypertensive 24 ABP and < 125/< 75 mmHg for normotensive 24 h ABP.