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Birth Control Patch May Up Clot Risk

Finding Is Preliminary and Needs More Study, Experts Caution
By
WebMD Health News
Reviewed by Louise Chang, MD

Feb. 17, 2006 -- Women using the Ortho Evra birth control patch may be twice as likely to develop blood clots as women using birth control pills, say researchers.

That's according to preliminary data from a new study. But the study is still being analyzed, and it's too early to be sure of the findings, experts caution.

Another study on the same topic didn't show patch users to be at higher risk of nonfatal clots than women using birth control pills. Ortho Women's Health & Urology, which makes the Ortho Evra patch, announced both studies' findings in a news release.

"We believe that these study results are important to make public so physicians have additional information to consider in making personalized decisions with their patients," Julie Keenan, spokeswoman for Ortho Women's Health & Urology, tells WebMD.

Doctors already knew hormonal contraceptives -- not just the patch -- boost the risk of clotting. The question is whether the patch carries a higher risk than other hormonal contraceptives.

The facts on that aren't final yet. Meanwhile, women using or considering the patch should talk to their doctors about their clotting risk, experts say.

About the Studies

The studies were based on information from two large databases of medical insurance claims. Funding for both studies came from Johnson & Johnson, which owns Ortho Women's Health & Urology, a division of Ortho-McNeil Pharmaceutical, Inc.

So far, only one of the studies has been published. That study showed patch users were at similar risk of nonfatal blood clots as women taking oral contraceptives containing 35 micrograms of estrogen.

The interim report of the second study shows patch users at approximately twice the risk of blood clots as women using oral contraceptives. That study's analysis isn't finished, so its meaning isn't clear yet. The study "will be published at a later date," states Ortho's news release.

FDA's Comments

Women using or considering the patch should talk to their doctors, the FDA's Daniel Shames, MD, FACS, told reporters in a teleconference. Shames directs the FDA's Division of Reproductive and Urologic Drug Products.

The studies included tens of thousands of women, says Shames. He didn't have exact figures for the clotting events seen in those studies; Keenan couldn't provide WebMD with those numbers, either.

The results are "preliminary" and need "further evaluation," says Shames. He notes that the researchers are checking to see if the patch users in the studies were more likely to be smokers or obese, compared with women taking birth control pills. That information might be available in May, Shames says.

'Fairly Unusual Events'

All hormonal contraceptives carry some degree of clotting risk, Shames says. He calls blood clots "fairly unusual events."

The FDA currently isn't seeking any changes in the patch's labeling, Shames says. He adds that last November, the patch's labeling was updated to note that its total estrogen exposure is about 60% higher than with oral contraceptives.

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