[Estrogens for prevention of coronary heart disease?]

In recent years, reports of favourable effects of estrogen therapy on cardiovascular morbidity and mortality have led to enthusiasm for widespread use of estrogens by postmenopausal women. Guidelines for estrogen therapy issued by the American College of Physicians include the statement "Women who have coronary heart disease are likely to benefit from hormone therapy". What evidence support this recommendation? More than 30 observation studies have examined the effect of estrogen replacement therapy on cardiovascular event and all cause mortality. In addition there have been 13 case controlled studies. The majority showed lower morbidity and mortality from coronary heart disease among users of postmenopausal estrogens than among non-users. Recently, 2 meta-analyses estimated the reduction in coronary heart disease associated with estrogen use to be in the range of 35 to 44%, respectively. All of these observational studies share a fatal flaw: Women who take estrogens are different from women who do not. Some differences have been measured, others have not. Women who take estrogens are on average better educated, healthier, have higher incomes and have better access to health care. These difference rather than the estrogens may account for much of the lower risk of heart disease. At this time we cannot tell from these observational studies what the real benefit of estrogens on coronary heart disease might be. Estrogen replacement therapy is not without risk. Estrogens increase the risk of endometrial carcinoma approximately 6-fold, an effect that is eliminated by the addition of progestins. Controversy continues over whether estrogen replacement increases the risk of breast cancer. A number of prospective randomized studies are now under way that will establish whether estrogen replacement therapy definitely reduces the risk of cardiovascular disease in women with and without coronary lesions and whether it increases the risk of breast cancer. Until the results of these trials are available claims on the definite usefulness of hormone supplementation to prevent coronary heart disease in postmenopausal women remain premature. In the light of the probable usefulness estrogen replacement therapy for the prevention of cardiovascular events should be recommended for women with increased risk for or definitively proven coronary heart disease.