抄録
The natural history of borderline hypertension was studied in a general population sample of 1, 621 Hisayama residents aged 40 or over, followed for 18 years. The causes of death during the study were verified by postmortem examination in most of the cases. The prevalence of borderline hypertension determined by a single casual blood pressure was almost equivalent at the 3 different cross-sectional surveys (1961, 1973-74, 1978) accounting for approximately 20% of the population. Prospectively, "borderline hypertension" was associated with an intermediate risk of cardiovascular mortality between normotensives and hypertensives. Borderline hypertensives with hypertensive organ damage manifested by left ventricular hypertrophy on electrocardiogram, retinal arterial changes and/or proteinuria, were much more related to cardiovascular deaths than those without. Blood pressure (BP) in persons not prescribed antihypertensive medications was examined at 3- or 6-year intervals during the follow up period, and the relationship of long-term changes in BP to subsequent cardiovascular mortality was determined. After adjusting for age, an elevation of BP to the hypertensive range from borderline was significantly associated with subsequent cardiovascular catastrophe, and a perspective labile BP was less related to that. The later evidence of hypertensive BP values in borderline was strongly correlated with initial BP levels in both systolic and diastolic, and also with old-age at the time of entry. It should also be emphasized that borderline hypertension was much more common than severely hypertensive disease in this community. If control of BP in this category is successful, a large number of cardiovascular deaths can hopefully be prevented, because the population-attributable risk of borderline hypertension is high.
