Health Canada renewed their advisories about the potential dangers of using the Evra contraceptive patch following results of a recent study. As the lawsuits and controversies mount, medical professionals continue to sing the same, sensible song.
The Evra Contraceptive Transdermal Patch were first marketed in the U.S. in 2002, as a simpler, more convenient alternative to oral contraceptives, only requiring a small patch to be applied to the skin once a week for three weeks to achieve protection against unwanted pregnancy. The patch became available in Canada in Jan. 2004.
By the end of 2005, the American Food and Drug Administration had received 21 reports of women dying from blood clots related to the use of the patch and ordered research into the safety of the product. The study concluded that women had a twofold higher risk of developing a venous thromboembolism--or VTE--when using contraceptive patches, according to the FDA.
Meanwhile, a study from the Boston Collaborative Drug Surveillance Program--ordered by Evra's parent company, Johnson & Johnson--deemed there was no higher risk associated with the patch over oral contraceptives containing 35 mg of estrogen, though their later study conceded that use of the patch resulted in estrogen levels up to 60 per cent higher than those produced by oral contraceptives.
The FDA issued advisories and mandated changes to the Evra label. Health Canada followed suit, mandating similar product warnings and public advisories. Two Canadian women have died and 15 others suffered blood clots or heart attacks since 2004 after using the Evra patch, according to a Health Canada report.
"These studies have limitations due to their design," reported Dr. Katharine O'Connell in a recent publication of the journal Clinical Obstetrics and Gynecology. She pointed out that current available data shows a range between a 0-60 per cent increase in estrogen levels, despite being drawn from the same data set, and that further research would be needed.
Consistent with other studies, Evra hastened to point out that the use of any hormonal birth control methods carry increased risk of VTE, and the new generation of estrogen used in both patches and pills, carries a lower risk of VTE than previous generations.
The studies also highlighted that other risk factors such as obesity, smoking, recent parturition, surgery or trauma were contributing factors in the deaths of the patch-using women, risk factors that would be present with oral contraceptive users.
Health Canada's most recent bulletin, published this month, supported Evra's conclusions.
The Evra patch--a "third-generation" hormone contraceptive--uses the same forms of synthetic estrogen and progestin as oral contraceptives, however these hormones are processed differently by the body. Oral contraceptives quickly reach a hormone-serum peak before being metabolized by the small intestine and liver, whereas patch contraceptives can maintain constant hormone levels for seven days or more. While the patch maintains a higher steady-state level of hormone, it has much lower peak values than oral contraceptives.
While scientists agree that having higher systemic estrogen over the long-term may have adverse consequences, O'Connell pointed out that it is still unknown whether any one factor can predict risk of VTE.
"The patch seems to lead to greater compliance [and] avoids the first-pass metabolism seen with oral contraceptives," said O'Connell in the report.
Health Canada and the FDA similarly conclude that the benefits of hormonal contraceptives greatly outweigh the drawbacks, and caution that their decision is based on sound medical advice.
"For women that choose to use contraceptives, it is important that they thoroughly discuss with their healthcare providers the risks and benefits involved," said FDA chief medical officer Janet Woodcock.
U of C Wellness Centre director Debbie Bruckner explained Evra patches are still being presented as an option to students, if it is appropriate for the individual.
"Every type of birth control has risks and benefits," said Bruckner. "When contraception is being discussed, we take into account the unique needs of the individual, their lifestyle and health. There are certain people [the patch] would not be prescribed for and the doctors are aware of these considerations."
Evra is currently conducting further research to reassess the average daily amount of hormones released from their patches, and are considering reducing the dose in line with oral contraceptive levels.
O'Connell cautioned that the patch is still a relatively new product and doesn't have the credibility that oral contraceptives have.
"Long-term studies will likely show similar benefits" she said. "Although the patch may not be a contraceptive panacea, increased birth control choices are good for all women and their partners."