Preliminary data on the risk of blood clots with the Ortho Evra contraceptive patch warrant further analysis but no immediate regulatory action, the FDA said today.
Ortho Women’s Health, a unit of Johnson & Johnson, released the data yesterday as part of results of two epidemiologic studies. Data in one of the studies shows an approximately two-fold increase in the risk of nonfatal venous thromboembolic events (VTEs) in users of the Ortho patch compared with users of an oral contraceptive.
The other study, however, showed VTE incidence was about the same.
The agency says a fuller evaluation is necessary to understand whether the findings really do diverge.
“It may be that the incidence rates between the two studies are essentially the same,” said Daniel Shames, MD, FDA director, Division of Reproductive and Urologic Drug Products.
They also could be higher or lower, he speculated, because the two studies’ confidence intervals—a mathematical description of how likely it is that others will have the same result as the study participants—overlap.
The controlled studies, both based on information from large medical insurance claims databases, were commissioned by Ortho about a year ago at the request of the FDA, which was interested in clarifying adverse events flowing in from its reporting system.
During questioning after a media briefing, Shames said that while the two studies involved tens of thousands of women, the absolute number of VTEs was low.
“These are fairly unusual events,” he said.
Investigators also are looking to see whether the adverse events were due to other underlying factors in the study cohorts, such as having more smokers or obese people in one group than the other.
Shames said Ortho could provide more information on these analyses by May and that an ongoing investigation comparing risk of heart attacks and strokes in women using the patch as compared to the pill would take another 18 months.
In November the FDA changed the Ortho patch label to warn women that they would be exposed to about 60% more estrogen than those who use birth-control pills.
For now, though, Shames said the FDA doesn’t plan on taking regulatory action.
Its explanation marks a continuing effort to openly discuss potential drug side effects and safety information.
“We’re trying to stay ahead of the curve…with the data as much as possible, even though data sometimes are not totally evaluated," Shames said.