Prediction of stroke by self-measurement of blood pressure at home versus casual screening blood pressure measurement in relation to the Joint National Committee 7 classification: the Ohasama study.

Background and Purpose: To compare the predictive power of self-measured home blood pressure (HBP) and casual blood pressure (CBP) for stroke risk in relation to the Joint National Committee 7 (JNC-7) classification.
Methods: HBP and CBP measurements were taken in 1702 subjects (> or =40 years) without a history of stroke, who were followed up for an average of 11 years. Subjects were classified into 4 groups on the basis of either HBP or CBP, according to the JNC-7 criteria: group 1 (HBP <115/75 mm Hg; CBP <120/80 mm Hg); group 2 (115/75< or =HBP<135/85 mm Hg; 120/80< or =CBP<140/90 mm Hg); group 3 (135/85< or =HBP<150/95 mm Hg; 140/90< or =CBP<160/100 mm Hg); and group 4 (HBP> or =150/95 mm Hg; CBP > or =160/100 mm Hg). Groups 2, 3, and 4 were further divided into 2 subgroups (a and b): those without and with cardiovascular disease risks, respectively. The risk of the first stroke in these groups was examined by the Cox hazards model adjusted for age and sex.
Results: The stroke risk in groups 3b and 4b (defined by HBP and CBP) was 2 to 5x higher than that in group 1 with significant differences. The risk in groups 2a, 3a, and even 4a was not significantly different from that in group 1 by the CBP-based classification, but the risk in group 4a was significantly higher than that in group 1 by the HBP-based classification, which also showed a stepwise increase in risk from groups 2a to 4a.
Conclusions: The JNC-7 classification had a stronger predictive power using HBP-based classification compared with CBP-based classification, suggesting the usefulness of HBP in the management of hypertension.