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Low Endogenous Estradiol, Raloxifene (Evista), Linked to Decreased Stroke Risk in Postmenopausal Women: Presented at ISC

By Paula Moyer

KISSIMMEE, FL -- February 21, 2006 -- Postmenopausal women who have low estradiol levels are at decreased risk of stroke, as are women with higher endogenous estradiol who take raloxifene (Evista), according to a team of investigators who presented their findings here at the annual International Stroke Conference (ISC).

"Women with lower blood levels of estradiol had a 70% lower risk of stroke whether they were taking raloxifene or placebo," said principal investigator Jennifer S. Lee, MD, PhD, in a presentation on February 17^th about the Multiple Outcomes of Raloxifene Evaluation (MORE). "Women with higher amounts of endogenous estradiol had a three-fold higher risk of stroke, but raloxifene reduced that risk by 60%."

Based on these findings, physicians may want to measure endogenous estradiol in order to assess women's stroke risk and guide their decisions regarding appropriate hormonal therapies for individual women, she said.

Dr. Lee noted that a low level of estradiol was defined as 10 pmol/L or lower, and a high level was defined as higher than 10 pmol/L. She is an Assistant Clinical Professor of Medicine, Division of Endocrinology and Metabolism, University of California at San Francisco, and Researcher, California Pacific Medical Center Research Institute, San Francisco, California, United States.

In the MORE study, 7705 postmenopausal women were randomized to either the raloxifene or placebo. MORE was originally designed to determine the effect of raloxifene on bone mineral density and vertebral fractures.

Dr. Lee and her team used the MORE data on 7290 women to assess patients' stroke risk. Subjects were at least 2 years postmenopausal but no more than 80 years old, were diagnosed with osteoporosis, and had no history of stroke or venous thromboembolic disease.

In the 2447 women in the placebo arm, there were 15 strokes reported (0.6). Among these women, 50% had undetectable endogenous estradiol, defined as less than 5 pmol/L, and the remainder had levels of at least 16 pmol/L.

Among the 4843 women on raloxifene, there were 14 strokes (0.3%). The investigators found that among these women, those with low estradiol levels had the same low risk of stroke as those on placebo. However, among the treated women, those with high estradiol levels had an relative risk of 0.4 for stroke compared to such women on placebo, a difference that "trended toward significant," said Dr. Lee.

Women with undetectable levels, the relative risk for stroke in the treated group was 1.9 compared to those on placebo, a difference that was not statistically significant, according to the investigators. Similarly, for those with baseline estradiol levels of 5 to 10 pmol/L, 0.8% of the 625 on raloxifene and none of the 341 on placebo had a stroke, a difference that was not statistically significant.

Evista is manufactured by Lilly, which funded the study. Dr. Lee has no financial ties to Lilly.


[Presentation title: Low Endogenous Estradiol Decreases Risk of Stroke and Estradiol Mediates the Effect of Raloxifene on Stroke in Older Women. Abstract LB2]

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