What information was found in the two studies [about the increased risk of blood clots]?
Both studies were conducted using electronic health care claims data. However, the results of the two studies are different. [The studies were funded by Johnson and Johnson, maker of the Ortho Evra birth control patch.] The first study was conducted by the Boston Collaborative Drug Surveillance Program. This study found that the risk of non-fatal VTE events associated with the use of the Ortho Evra contraceptive patch is similar to the risk associated with the use of oral contraceptive pills (OCs) containing 35 micrograms of ethinyl estradiol (an estrogen) and norgestimate (a progestin hormone). The second study, which also included patient chart review, was conducted by another group of investigators (i3 Ingenix). Results of this second case-control study show an approximate 2-fold increase in the risk of medically verified VTE events in users of Ortho Evra compared to users of norgestimate-containing oral contraceptives containing 35 micrograms of estrogen. Longer follow-up for VTE,
