Both high and low blood pressures risk indicators of death in middle-aged males. Isotonic regression of blood pressure on age applied to data from a 13-year prospective study.

This study was performed to investigate whether a moderately sized population of men (n = 954) living in a geographically defined area could be utilized and give valid results in a 13-year prospective study regarding mortality as a function of blood pressure. Isotonic regression of blood pressure on age was used to define groups of men with low, medium, and high blood pressure. Men aged 40-69 years in both extreme groups showed an excess death risk in comparison with those in the medium group. Thus, mortality appeared to be a U-shaped function of blood pressure in this age group. The mortality ratios of the low and high blood pressure groups vis-à-vis the medium group were higher during the first than during the second half of the observation period. Chronic diseases at the time of the initial examination were more common among men who died in the lowest blood pressure group than among those who died in the medium group. In males aged 70-99 years, blood pressure appeared to be of less importance as a risk indicator of death.