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.
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.
The clinical importance of higher estrogen exposure with the patch isn't known yet, Shames says.
"For some people, the patch may be better because some people don't reliably take the pill or they don't want to take the pill, or they forget the pill," he says. "The patch does offer them some alternative for contraception." On the other hand, Shames says the new findings need to be interpreted.
It's important to share new information on drug safety quickly, but that may mean releasing information before final analysis is done, Shames notes. "If there is a downside to being more transparent, this may be it," he says.
WebMD spoke with Sutel Pardanani, MD, of the obstetrics, gynecology, and women's health department at New York's Montefiore Medical Center.
"I think this data is very new," Pardanani says. "It's important to take this information in its context and really follow up the information in the next few months to see if this truly is a concern."
Pardanani encourages women using or considering the patch to talk to their doctors.
"I would actually have these women who are on the Ortho Evra patch to contact their physicians before this turns into a panic of sorts, just to discuss this risk," Pardanani says, stressing that women should remember that the facts aren't final yet, that all hormonal contraceptives carry clotting risk, and that no one is certain yet how the patch rates in that regard.
Discuss Risk Factors
Before using any hormonal contraceptive, women should discuss their risk factors with their doctors, Pardanani says. Those risk factors include smoking -- especially for women age 35 and older -- and family history of recurrent clots.
Pardanani also suggests that women report symptoms such as leg pain, chest pain, shortness of breath, or swelling or redness in either leg to their doctors. However, she cautions that clotting symptoms "may be even more subtle than that, so I would actually have the patient contact her physician to go through the whole list of things."