Thrombotic risk of contraceptive transdermal patches and the contraceptive vaginal ring.Prescrire Int. 2013 Nov; 22(143):266, 268-9.PI
The annual risk of venous thrombosis has been estimated at 5 to 10 cases per 100 000 women aged 15 to 44 years who are not using hormonal contraception.The risk increases with age for all women. Combined oral oestrogen-progestin contraceptives increase the risk of venous and arterial thrombosis. The risk of venous thrombosis varies, depending on which oestrogen-progestin combination is used. It is about 20 cases per 100,000 woman-years with contraceptives combining norethisterone or levonorgestrel with ethinylestradiol at doses below 50 microgram.The risk is twice as high with third-generation oral contraceptives. In addition to the oral route, hormonal contraception is available as a a transdermal patch or a vaginal ring. What is the risk of thrombosis associated with these non-oral forms? A cohort study showed that the risk of venous thrombosis was approximately 8-fold higher among women using a transdermal patch and 7-fold higher in those using a vaginal ring compared to women not using contraception. Another study on arterial thrombosis demonstrated a statistically significant increase in the risk of stroke among vaginal ring users, but not in the risk of myocardial infarction. In practice, overall, these data show that the use of contraceptive transdermal patch or the contraceptive vaginal ring increases the risk of venous thrombosis.The excess risk of arterial thrombosis is unknown.When hormonal contraception is requested, it is better to recommend a combination containing levonorgestrel and less than 50 microgram of ethinylestradiol per tablet, which carries a lower risk of venous or arterial thrombosis.