Essential hypertension in women

OVERVIEW

Before age 50, women have a lower prevalence of hypertension than men, but after age 55, they have a higher prevalence [1]. The eventual prevalence of hypertension in women is similar to that in men, averaging 30 to 40 percent in blacks and roughly 20 percent in whites. The prevalence rises with age, approaching 80 to 90 percent in women over the age of 70 if subjects with isolated systolic hypertension are included (graph 1) [1,2]. (See "The prevalence and control of hypertension".)

There are, however, several important gender-related differences:

• The incidence of hypertensive complications is significantly lower in women than in men, particularly in premenopausal women [3,4]. The decrease in risk is primarily due to a reduced incidence of coronary heart disease (which is only one-half that in men at the same blood pressure), while the difference in the risk of stroke is much less prominent [3]. Left ventricular hypertrophy is less common in women than in men with similar degrees of hypertension [5].
• A greater BP load seems to be required to produce cardiovascular injury in women. This difference is taken into account in a report from New Zealand that recommends that therapy be given only to those patients with an estimated overall 10-year risk for cardiovascular complications of at least 20 percent [6]. At equal degrees of hypertension, women were at lower risk than men in all age groups from 40 to 70 (algorithm 1).

The reasons for these differences are not clear, but hypertensive women have somewhat different hemodynamic findings from men (matched for blood pressure, race, age, and body surface area) [7,8]. Women tend to have a 10 percent higher cardiac output and a 10 percent lower systemic vascular resistance (SVR). Women also then to have a wider pulse pressure, related to shorter stature (resulting in a more rapid return of the pulse wave to augment the peak pressure), and a faster heart rate (induces a short diastolic period) [9].

Women also have only two-thirds as great a rise in blood pressure with exercise. Premenopausal women have less effective baroreflex buffering of blood pressure than men of similar age, which may explain less effective blood pressure regulation in women in response to vasoactive drugs and acute stress [10].