With many women still searching for the perfect birth control method, a systematic review analyzes a host of studies comparing the contraceptive skin patch or vaginal ring to the pill. Although perfection remains elusive and choices are equally effective, the review authors were able to pinpoint some preferences.

“Basically, all of these methods were similar in preventing pregnancy,” said lead investigator Laureen Lopez, Ph.D., research associate at Family Health International in Research Triangle Park, N.C.

Last week, the U.S. Food and Drug Administration added warning data to the drug label for the contraceptive skin patch, advising users that the women using the patch have a greater risk of blood clots than pill users. The study prompting the FDA action was not part of the review.

For the review, the researchers looked at 11 randomized controlled trials — three comparing the patch to the pill, and eight comparing the ring to the pill — comprising more than 6,000 women.

Women using the patch were more likely to use the medication as prescribed than those on the pill were. However, patch users experienced more side effects and were more likely to abandon their method eventually than pill users were.

Ring users generally had fewer serious side effects than pill users, but had more vaginal irritation and discharge. Despite this, vaginal ring users tended to stick with their approach longer than the pill group.

The patch is a small adhesive square that dispenses hormones and which a woman must replace every week for three weeks, and then leave off for a week. The Ortho Evra contraceptive patch is the only patch approved for use to date.

The NuvaRing, which Organon manufactures, releases hormones into the vaginal cavity. A woman inserts the ring, a flexible piece of plastic tubing, where it remains for three weeks; she then removes it for one week. Many consider the ring and patch easier to use than birth control pills because women do not have to attend to them every day.

Compared with pill users, patch users had more bleeding breakthroughs, breast discomfort, painful periods, and nausea and vomiting. Rings users, on the other hand, had more vaginal irritation and discharge. Of the two, patch users tended to discontinue the method more readily.

The contraceptive review updates one done in the past, for which only two studies of the patch versus the pill were available. The ring data are new. For all methods, several studies had women drop out, which can limit the value of the results according to the researchers.

“Women who used the ring had fewer bleeding problems than those on the pill, but they did have irritation,” Lopez said. “But discontinuation was similar for the ring and the pill in most of the studies.”

Clinicians have seen the ring increase in popularity, Lopez added.

Mitchell Creinin, M.D., professor and director of gynecological specialties at the University of Pittsburgh, is familiar with all of the review studies. “It all comes back to compliance.” Creinin said. “Once a week versus once a day, twice as much hormone entering the body (with the patch), or half as much (with the ring).”

Creinin, who was not involved with the review, said it is important to understand the people who would enter these studies: “These studies were done primarily when only the pill was available. Women who were unhappy with their present method of birth control were the ones likely to enter them.” He noted that the results differ among studies between European and American women. “North American women tend to have more complaints and are less compliant,” he said.

Overall, Creinin said, women are happy with their birth control because they are not getting pregnant.

Lopez said that women have to consider many issues when choosing a method of birth control. Ease of use, side effects and life situation are each important. For a contraceptive to be effective, the woman must be willing and able to follow the prescribed regimen.

“Women are finally beginning to understand that taking a pill every day is difficult.” Creinin said. He is working on an upcoming study comparing the ring to the patch.

The Cochrane Collaboration is an international nonprofit, independent organization that produces and disseminates systematic reviews of health care interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions.

Lopez LM, et al. Skin patch and vaginal ring versus combined oral contraceptives for contraception (Review). Cochrane Database of Systematic Reviews 2008, Issue 1.

Source: Health Behavior News Service