Hypertension and Risk Stratification (2008)

Japan has become a super-aged society (the percentage of the elderly ≥20% of the population), and medicine is shifting to “preventive medicine” for the prevention of severe cardiovascular diseases to use limited medical resources effectively. In particular, the specific health checkup for Japanese aged 40– 74 years, which was initiated in April 2008, is considered to be a large-scale intervention study aiming at preventing cardiovascular diseases and has attracted global attention. The specific health checkup focuses on the early detection of metabolic syndrome. The diagnostic criteria of this syndrome (1) were proposed not only by introducing visceral obesity as a new concept, but also by paying attention to the clustering of cardiovascular risks before the development of disease. The blood pressure criterion for metabolic syndrome is equal to or more than 130/85 mmHg, which corresponds to a highnormal value according to the Japanese Society of Hypertension Guidelines for the Management of Hypertension (JSH 2004) (2). The cluster of blood pressure higher than this criterion, visceral obesity, and lipid metabolism abnormality synergistically increases the risk of cardiovascular disease. As shown in Fig. 1, the Seventh Report of the Joint National Committee on Prevention (JNC-7) (3) in the U.S. abolished risk stratification and simplified the criteria so that treatment principles could be determined based on blood pressure alone. In contrast, the European Society of Hypertension (ESH)/the European Society of Cardiology (ESC) Guidelines for the Management of Arterial Hypertension (4) classified the non-hypertensive group into two (normal, high-normal) groups, and proposed treatment based on detailed risk stratification. In the guidelines in Japan or China (5), the risk stratification in the hypertensive group is similar to that in the ESH/ESC guidelines, but risk assessment in the non-hypertensive group is described only in the text. The proposal of a risk stratification system for the development of strokes or transient ischemic attack (TIA) by Asayama et al. in this issue of Hypertension Research (6) showed a classification of blood pressure into 6 grades from optimal to Stage 3, that of risk factors into 3 strata, and that of severity assessment into 4 grades (no–high). The unique point in their proposal was the classification of non-hypertensive group into 3 grades. The risk stratification in their paper was similar to that of the ESH/ ESC guidelines, but differed in that a very high risk group was not established because clinical intervention methods are similar between high and very high risk groups, and an optimal blood pressure group was established. In Fig. 1, for the comparison of evaluation based on casual blood pressures as in other guidelines, we presented the table in Fig. 2C of Asayama et al. (6), showing relatively well-separated casual blood pressures after minor adjustments based on absolute risks. The unique point of Asayama et al.’s proposal that differs from other guidelines is that the Stage 2 group with 1–2 risk factors (* in the figure) was classified as high severity. If classification based on home blood pressures effective for predicting prognosis as a characteristic of this paper is adopted, the risk stratification shown in Fig. 2B of Asayama et al. (6) is excellent. In this stratification, this group (* in the figure) is classified as moderate severity, as is observed in other guidelines. The other important findings in Asayama et al. (6) were an increased stroke risk even in the high-normal and normal blood pressure groups compared with the optimal blood pressure group and a definite increase in the relative risk of the presence of multiple risk factors even in the same blood pressure group. The only difference between Fig. 2A and B of