Association between blood pressure and mortality in 80-year-old subjects from a population- based prospective study in Japan

Hypertension is one of the greatest risk factors for cardiovascular disease, but the contribution of high blood pressure to cardiovascular morbidity and mortality is weakened with aging. In the present study, we examined whether high blood pressure would be a risk factor for total and cardiovascular mortality in a group of very elderly Japanese. Six hundred and thirty-nine participants who were 80 years old in 1997 were enrolled. The subjects were divided into three groups on the basis of their systolic blood pressure (SBP) (below 140 mmHg [group 1, n=212], from 140 mmHg to 159 mmHg [group 2, n=217], over 160 mmHg [group 3, n=210]). During the 4-year follow-up period, 87 individuals died and 24 of these deaths were due to cardiovascular diseases. Cox multivariate regression analysis revealed that there was no association between total mortality and SBP levels (relative risk [RR] 1.71; confidence interval [CI] 0.81-3.58; group 3 compared with group 1, p=0.35). However, the subjects taking antihypertensive medication showed significantly higher mortality with increasing SBP level (RR 5.72, Cl 1.03-31.6, p=0.04, group 3 compared with group 1). Furthermore, in the subjects with a cardiovascular disease such as angina or stroke, high SBP increased the total mortality (RR 13.4, Cl 2.39-75.1, p=0.004, group 3 compared with group 1). The present study did not find an association between blood pressure and mortality in the very elderly. However, our results did suggest that high SBP increases the risk of mortality in patients with cardiovascular diseases and/or taking antihypertensive medication.