Isolated systolic hypertension: how common? How risky?

The following summary of the physiologic and epidemiologic evidence may help the clinician in making decisions when caring for persons with ISH: ISH is predominantly found in older age groups, being present in 1% to 4% of the population under age 40, 10% to 15% between ages 60 and 70, and 25% to 30% over age 70. ISH is more prevalent in women than in men. The development of ISH in the aged is associated with a decrease in arterial compliance. The relationship whereby ISH is both a cause and a result of atherosclerotic vessels needs further delineation. Neurohumoral factors also have a part in determining arterial compliance. An elevated SBP is an important contributor to the risk of developing coronary artery disease, and in persons over 45 years old it is a more powerful predictor of coronary events than DBP. SBP is a better discriminator of risk for strokes at all ages than DBP is. The relative risk in persons with ISH for the development of coronary artery disease and stroke is two to five times that of normotensive persons, but is no worse than the risk for these events among treated hypertensives. Although the relative risk of ISH is not strikingly large, the high prevalence of ISH among aged individuals, the increasing size of the population over 65 years old, and the high incidence rate of cardiovascular events in the aged give ISH a sizable attributable risk in the population (13 to 28 deaths per 1,000 individuals). It remains to be shown that lowering SBP in ISH removes the risk of ISH. Studies are needed that monitor the costs and adverse effects of therapy as well as the possible benefits when a condition such as ISH is most commonly seen in the aged.