In the Yaz lawsuits pending around the country, plaintiffs’ lawyers argue that blood clots are unacceptable risk of Bayer’s decision to add drospirenone to birth control pills. It is not just plaintiffs’ attorneys beating that drum. Numerous studies have been published in recent years which showed an increase in risk of blot clot formation in birth control users, and showed decrease in risk with decreases in estrogen dose. But does Yaz/Yasmin cause particular risks?
Earlier this week the British Medical Journal (BMJ) published a study on Danish women, aged 15-49 during 1995-2009, focusing on results after the release of oral contraceptives containing drospirenone. Information was compiled for more than 1.7 million women. Stating the obvious, this is a huge study group. The study was designed so that any confounding factors such as body mass index, smoking, surgery, and social class were addressed, to ensure a robust analysis of the data. As a result, a total of 1.3 million women were included in the analysis. Women were categorized based on birth control pill use, type, dose, and length of use.
A total of 4,307 cases of venous thrombosis (blood clot in the vein) were identified, though not all occurred in women using combined contraceptives. Of these cases, 26% resulted in pulmonary embolism (blood clot travelling to the lung), 63.6% were deep venous thrombosis, and 6.6% were unspecified. The remaining were among cerebral venous thrombosis (blood clot in the veins of the brain), vena cava thrombosis, and kidney venous thrombosis. Approximately 2% suffered a stroke.
The study showed that current users of birth control pills containing levonorgestrel, were 3 times more likely to have a confirmed venous thrombosis (blood clot in the vein), and women using desogestrel, drospirenone, gestodene or cyproterone acetate were 6 to 7 times more likely to have venous thrombosis, two times greater risk than levonorgestrel.
This study showed that drospirenone that is in Yaz and Yasmin was not the only combinational contraceptive to be linked to blood clots. Other combination oral contraceptives containing desogestrel (e.g. Cyclessa, Deogen, Emoquette, Kariva, Mircette, Ortho-Cept and Velivet), gestodene or cyproterone acetate, as well as levonergestrel, were also at increased risk. Gestodene and cyproterone acetate containing birth control pills are not currently on the market in the United States.
Yesterday, the FDA released its final report on combination oral contraceptives, a retrospective study conducted on 835,826 women aged 10-55. The study found that use of drospirenone/ethinyl estradiol tablet, norelgestromin/ethinyl estradiol transdermal patch and etonogestrel/estradiol vaginal ring were all associated with increased risk of venous thromboembolism, both deep vein thrombosis and pulmonary embolism. The finding that the etonogestrel/estradiol vaginal ring was associated with increased risk of venous thromboembolism is a new finding that warrants further investigation, raising new concern for this device. The risks of combination oral contraceptives will be further discussed by the FDA at an advisory board meeting on December 8, 2011.
I think there is going to be a “soft” Yaz recall in the next two years in which Bayer takes Yaz and Yasmin off the market, citing the decline in sales. Meanwhile, women will continue to suffer from Yaz/Yasmin related deep vein thrombosis and pulmonary embolism.