Although hypertension treatment in women is recommended to decrease the risk of cardiovascular disease (Wenger 1993, Kaplan 1995, Kuhn 1993, Hayes 1998, JNCVI,1997), the evidence for treatment benefit is primarily based on combined results for men and women (Collins 1990, Insua 1994, Mulrow 1994, Psaty 1997).
To assess whether the relative and absolute benefit of hypertension treatment in women varies with age or race.
Literature search of studies from 1966 to 1998 using MEDLINE, reviews, and consultation with experts.
Studies were eligible if they were randomized controlled trials of pharmacological treatment of primary hypertension, with cardiovascular morbidity and mortality outcomes, and with over one hundred women enrolled.
Data collection and analysis
The pooled population included 23,000 women. Relative risks were combined for each endpoint to form summary risk ratios (RR) using meta-analytic techniques based on a random-effects model. Summary RR's were converted to numbers needed to treat (NNT). Data were dichotomized by age to approximate menopausal status (30 to 54 years, and 55 years and older), and by race (white and African American).
In women ages 55 years or older (90% white), hypertension treatment results in a 38% risk reduction in fatal and nonfatal cerebrovascular events (95% confidence interval (CI) 27-47%, 5 year NNT 78), a 25% reduction in fatal and nonfatal cardiovascular events (95% CI 17-33%, 5 year NNT 58), and a 17% reduction in cardiovascular mortality (95% CI 3-29%, 5 year NNT 282). In women ages 30 to 54 years (79% white), hypertension treatment results in a 41% risk reduction in fatal and nonfatal cerebrovascular events (95% CI 8-63%, 5 year NNT 264), and a 27% risk reduction in fatal and nonfatal cardiovascular events (95% CI 4-44%, 5 year NNT 259). Hypertension treatment in African American women (mean age 52 years) reduced the risk of fatal and nonfatal cerebrovascular events by 53% (95% CI 29-69%, 5 year NNT 39), fatal and nonfatal cardiovascular events by 45% (95% CI 18-63%, 5 year NNT 21), fatal and nonfatal coronary events by 33% (95% CI 6-52%, 5 year NNT 48), and all cause mortality by 34% (95% CI 14-49%, 5 year NNT 32). Analyses in white women 30 to 54 years old did not show any statistically significant treatment benefit or harm.
Hypertension treatment lowers the relative and absolute risk of cardiovascular morbidity and mortality in women ages 55 years and older, and in African American women of all ages. A greater effort should be made to increase awareness and treatment in these groups of women. Although relative risk reductions for cerebrovascular and cardiovascular events are similar for younger and older women, the NNT of younger women is at least 4 times higher. Decisions for treatment of hypertension in younger white women should be influenced by the individual patient's absolute risk of cardiovascular disease.