By Ed Susman
SAN DIEGO, CA -- May 9, 2007 -- The ethinyl oestradiol/drospirenone oral contraceptive does not appear to show any signal of causing excess venous thromboemboli, researchers said here at the 55th annual clinical meeting of the American College of Obstetricians and Gynecologists (ACOG).
Because the relatively rare risk of venous thromboemboli is not often seen in clinical trials, post-marketing surveillance is required to determine if there is a clotting problem associated with new medications, said John D. Seeger, PharmD, DrPH, senior scientist, i3 Drug Safety, Ingenix, Waltham, Massachusetts, United States.
In the study, Dr. Seeger and colleagues scrutinised the incidence rate of venous thromboembolism for Yasmin using data culled from the Ingenix Research Data Mart for between July 2001 and June 2004. That data were compared with the incidence rate of venous thromboemboli among other initiators of oral contraceptives.
"We found that women initiating ethinyl oestradiol/ drospirenone are no more likely than other oral contraceptive initiators to experience the event of venous thromboembolism," Dr. Seeger said.
The researchers matched 22,429 ethinyl oestradiol/drospirenone oral contraceptive initiators with 44,858 other oral contraceptive users. The study included women who were 10 to 59 years of age at the time of initiating the use of contraceptives.
Among the ethinyl oestradiol/drospirenone oral contraceptive used there were 14,541woman-years of use and 18 venous thromboembolism events -- a rate of 1.2 per 1,000 women-years.
Among the other oral contraceptive used, there were 28,169 woman-years of use and 39 venous thromboembolism events -- a rate of 1.4 per 1,000 women-years.
The relative-risk ratio of 0.9 indicates no significant difference in outcomes between ethinyl oestradiol/drospirenone initiators and other oral contraceptive initiators.
"Risk factors -- including thromboembolism risk factors -- were well balanced between ethinyl oestradiol/drospirenone initiators and other oral contraceptive initiators, but absolute incidence rates reflect the fact that women were not excluded for having risk factors," Dr. Seeger said.
The study was supported by Bayer HealthCare Pharmaceuticals, Wayne, New Jersey, United States.
[Presentation title: Venous Thromboembolism Among Women Using Ethinyl Estradiol With Drospirenone and Other Oral Contraceptives. Abstract 8 (May 8)]
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