Risk of VTE Increased in New Users of Drospirenone
A retrospective cohort study of more than a half million new users of hormonal contraception shows that drospirenone is associated with a higher risk of thrombotic events than contraceptives containing low-dose estrogen.
Funded by the U.S. Food and Drug Administration and led by researchers at Kaiser Permanente, the analysis included 573,680 women ages 10 to 55 from Kaiser Permanente Northern California, Kaiser Permanente Southern California, and state Medicaid programs in Tennessee and Washington. The women were selected because they had first exposure to one of four combination OCs, the norelgestromin-containing transdermal patch (NGMN), or the etonogestrel vaginal ring (ETON) between 2001 and 2007. The comparator OCs were pills containing drospirenone/ethinyl estradiol (DRSP), levonorgestrel/ethinyl estradiol (LNG10-20), levonorgestrel/ethinyl estradiol (LNG15-30), norethindrone/ethinyl estradiol (NETA), and norgestimate/ethinyl estradiol (NGM).
New users of DRSP had 1.77 times the risk of venous thromboembolism (VTE) (95% confidence interval [CI] 1.33-2.35) and 2.01 times the risk of aterial thrombotic events (ATE) (95% CI 1.06-3.81) than the new users of LNG10-20, LNG15-30, NETA, or NGM. The increased risk of DRSP was limited to those ages 10 to 34 years for VTE and ages 35 to 55 years for ATE.
Use of the NGMN patch and the ETON vaginal ring were not associated with increased risk of either thromboembolic or thrombotic outcomes. The authors, noted, however, that the patch and ring are used by far fewer women.
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