Proposal of a risk-stratification system for the Japanese population based on blood pressure levels: Ohasama study

The aim of the present study was to propose a risk-stratification system based on self-measurement of home blood pressure (HBP) as well as casual-screening BP (CBP) in relation to Japanese Society of Hypertension Guidelines for the Management of Hypertension (JSH 2004). For 4 weeks, the subjects measured their HBP while seated every morning within 1 h after awaking, after having rested for at least 2 min. The subjects included 2,368 Ohasama residents aged ≥35 years, with no history of stroke. CBP was measured twice consecutively at baseline. Among all subjects, there were 174 incidences of stroke or transient ischemic attack (TIA) observed during 9.4 years (interquartile 7.0-12.4) of follow-up. The analysis revealed statistically significant linear increases in stroke or TIA risk in both the CBP-based and HBP-based classifications. The risk for high-normal blood pressure (BP) was not significantly high according to the CBP-based classification (relative hazard [RH] 1.52; 95% confidence interval [CI] 0.89-2.60), whereas it was significantly high by the HBP-based classification (RH 1.91; 95% CI 1.04-3.51). On the basis of the data in the absolute risk table, the risks of first stroke or TIA for the 4 groups in the CBP-based and HBP-based classifications were proposed. Stroke or TIA risk increased linearly with the increase in the stage of stratified risk, regardless of BP information (trend p<0.0001). Risks for non-hypertensive individuals should be assessed in the next version of the Japanese BP guidelines. Furthermore, the importance of HBP should be emphasized in order to accurately evaluate BP risks for individuals.