Register for Patch And Birth Control Pills Are Similarly Effective In Preventing Pregnancy
ContraceptionJune 7, 2001
2001 JUN 7 - (NewsRx.com & NewsRx.net) -- 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 µg of ethinyl estradiol (a commonly used form of the hormone estrogen) and 150 µg 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 re-applied.
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 occurred in individuals who were using the patch correctly.
"Overall and method-failure Pearl Indexes were numerically lower with the patch (1.24 and 0.99, respectively) vs. the OC (2.18 and 1.25, respectively); this difference was not statistically significant," the authors reported (JAMA, 2001;285:2347-2354).
The incidence of unexpected bleeding with a hormonal contraceptive is commonly reported as a reason for discontinuation of a particular method. In this study, breakthrough bleeding and spotting was defined as any bleeding and spotting occurring on days 1 through 21 of a cycle, excluding bleeding in connection with the menstrual period.
"The incidence of breakthrough bleeding and/or spotting was significantly higher only in the first two cycles in the patch group, but the incidence of breakthrough bleeding alone was comparable between treatments in all cycles," Audet et al. found.
"Both treatments were similarly well tolerated; however, application site reactions, breast discomfort, and dysmenorrhea [pain or discomfort during or just before a menstrual period] were significantly more common in the patch group," they said.
"The rate of adhesion of a contraceptive patch will also contribute to contraceptive efficacy, cycle control, and patient satisfaction," Audet, Koltun, and co-authors added. A total of 4.6% of all patches were replaced for complete (1.8%) or partial (2.8%) detachment.
Compliance with the dosing schedule of the patch was better than that of the oral contraceptive. "The mean [average] proportion of each participant's cycles that demonstrated perfect compliance was 88.2% (811 total participants, 5,141 total cycles) with the patch and 77.7% (605 total participants, 4,134 total cycles) with the OC," they reported.
"The transdermal combination hormonal contraceptive patch uses weekly dosing to complete a 21-day regimen followed by one dose-free week. The weekly dosing was associated with significantly better compliance than is observed with daily dosing regimens," noted the researchers.
They speculated that the improved compliance with the patch may reduce pregnancy rates. However, this study demonstrated no difference in pregnancy rates between the two methods.
This work was supported by the R.W. Johnson Pharmaceutical Research Institute, Raritan, New Jersey. This article was prepared by Women's Health Weekly editors from staff and other reports.
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