Yesterday’s issue of the Archives of Internal Medicine published the final study of the Women Health Initiative (WHI), the largest trial examining the benefits and risks of estrogen replacement therapy in post-menopausal women. The news is not good.

The results of the study are reviewed in this article.

Previous studies on the WHI data showed that combination therapy with estrogen and progesterone increased the risk of stroke and blood clots in veins. At that time many physicians still defended estrogen replacement therapy, proposing that it is likely the progesterone that causes these increased risks. They were wrong.

This latest study looked at women who were randomized to take estrogen alone (without progesterone) versus a placebo. The women taking estrogen had an almost 30 percent higher risk of venous blood clots then the women on placebo. That was about one additional blood clot for every 200 women taking estrogen.

The risk of estrogen therapy is now undeniable. Its continued use for osteoporosis, for which other safer medications exist, can no longer be justified. It should only be used to treat severe symptoms of menopause (such as hot flushes, sleep disturbance) that the patient finds intolerable. Even in these cases the lowest dose of estrogen should be used and frequent attempts should be made to wean the estrogen off.

I’ve been quite surprised by the hesitancy of some practitioners to act on this data. Many patients are hearing mixed messages from physicians that the risks are small or that the health benefits are worth it. These claims should no longer be made.

If you or a loved one is still taking estrogen replacement, bring this study to the attention of your internist. If the estrogen isn’t being used to treat intolerable hot flushes or sleep disturbance, consider (with your doctors advice) slowly tapering the estrogen off.