Women who start hormone therapy closer to menopause may have a lower risk for coronary heart disease than women who begin treatment further from menopause, but the reduction in risk does not appear to be statistically significant, according to an article in the April 4 issue of the Journal of the American Medical Association.

Studies examining the effects postmenopausal hormone therapy on coronary heart disease have yielded mixed results, depending on the type of study conducted. There may be a number of reasons for the differences, including the timing of initiation of hormone therapy, according to background information in the article.

Jacques E. Rossouw, MD, of the National Heart, Lung, and Blood Institute, Bethesda, MD, and colleagues conducted a secondary analysis of data from the Women's Health Initiative (WHI) trial to determine whether effects of hormone therapy on risk of cardiovascular disease varied by age or years since beginning of menopause. The trial included 10,739 postmenopausal women who had undergone hysterectomy who were randomized to conjugated equine estrogens (CEE) or placebo and 16,608 postmenopausal women who had not had a hysterectomy who were randomized to the estrogens plus medroxyprogesterone acetate (CEE + MPA) or placebo. Women aged 50 to 79 years were recruited from 40 US clinical centers between September 1993 and October 1998.

"Although not statistically significant, these secondary analyses suggest that the effect of hormones on coronary heart disease may be modified by years since menopause and by the presence of vasomotor symptoms such as hot flashes or night sweats, with higher risks in women who were 20 or more years since menopause (or aged 70 years or greater). Coronary heart disease tended to be nonsignificantly reduced by hormone therapy in younger women or women with less than 10 years since menopause, and the risk of total mortality was reduced in women aged 50 to 59 years," the authors wrote.

"We did not have adequate statistical power to assess outcomes in the women aged 50 to 54 years or less than 5 years since menopause. As previously reported, estrogens appeared to be associated with lower risk of coronary heart disease than combined hormone therapy. Importantly, the risk of stroke was not influenced by years since menopause, the presence of vasomotor symptoms, or drug regimen, although there was no increased risk of stroke in women aged 50 to 59 years."

"The absence of excess absolute risk of coronary heart disease and the suggestion of reduced total mortality in younger women offers some reassurance that hormones remain a reasonable option for the short-term treatment of menopausal symptoms, but does not necessarily imply an absence of harm over prolonged periods of hormone use. In contrast, risk of stroke did not depend on years since menopause or the presence of vasomotor symptoms. The findings are consistent with current recommendations that hormone therapy be used in the short-term for relief of moderate or severe vasomotor symptoms, but not in the longer term for prevention of cardiovascular disease," the authors concluded.