Patch And Birth Control Pills Are Similarly Effective In Preventing Pregnancy.

2001 JUN 7 - (NewsRx Network) -- The contraceptive patch is comparable to a combination oral contraceptive in pregnancy prevention and cycle control, and compliance is better with the patch than with the pill, study results indicate.

Marie-Claude Audet, MD, of Centre Medical des Halles de Ste-Foy, Ste-Foy, Quebec, Canada, and William Koltun, MD, of the Medical Center for Women's Clinical Research, San Diego, California, and colleagues conducted a randomized trial to compare the contraceptive efficacy, cycle control, compliance, and safety of an oral contraceptive (OC) and a transdermal patch, which allows the dosage to be administered through the skin. They published their findings in the May 9, 2001, issue of the Journal of the American Medical Association.

The trial, conducted at 45 clinics in the United States and Canada from October 1997 to June 1999, comprised 1,417 healthy adult women of child-bearing potential.

According to background information cited in the article, oral contraceptive pills are effective, but poor compliance increases rates of pregnancy during treatment. The ability of the transdermal contraceptive patch to deliver hormones as a form of contraception has been evaluated in several trials. The patch is designed to deliver 20 [micro]g of ethinyl estradiol (a commonly used form of the hormone estrogen) and 150 [micro]g of norelgestromin (a chemical that breaks down into a type of the hormone progestin).

In this study, 812 women were randomly assigned to receive transdermal patches, and 605 received oral contraceptives, for either six or 13 cycles. Those who received the patch could maintain their usual activities, including bathing and swimming, while wearing the patch - but were told not to apply oils, creams, or cosmetics on or around the area where the patch was placed. They were instructed to apply one patch on the same day of each week for three consecutive weeks, then not wear a patch for one week. If patches detached, they could be immediately reapplied.

To evaluate contraceptive efficacy, Audet et al. used the Pearl Index (number of pregnancies per 100 person-years of use) and life-table estimates of the probability of pregnancy. The overall Pearl Index included all pregnancies that occurred in individuals who received either drug for at least one day and were not pregnant at the beginning of the study. The method-failure Pearl Index included only those pregnancies that ...