Evaluation of contraceptive efficacy and cycle control of a transdermal contraceptive patch vs an oral contraceptive - A randomized controlled trial

Context Oral contraceptive (OC) pills are effective, but poor compliance in creases rates of pregnancy during treatment. Objective To compare the contraceptive efficacy, cycle control, compliance, and safety of a transdermal contraceptive patch and an OC, Design Randomized, open-label, parallel-group trial conducted October 1997 to June 1999. Setting Forty-five clinics in the United States and Canada. Participants A total of 1417 healthy adult women of child-bearing potential . Interventions Participants were randomly assigned to receive a transdermal contraceptive patch (n=812) vs an OC (n=605) for 6 or 13 cycles. Patch trea tment consisted of application of 3 consecutive 7-day patches followed by 1 patch-free week. Main Outcome Measures Overall and method-failure Pearl Indexes (number of p regnancies/100 person-years of use) and life-table estimates of the probabi lity of pregnancy were calculated. Cycle control, compliance, patch adhesio n, and adverse events were also assessed. Results Overall and method-failure Pearl Indexes were numerically lower wit h the patch (1.24 and 0.99, respectively) vs the OC (2.18 and 1.25, respect ively); this difference was not statistically significant (P=.57 and .80, r espectively), The incidence of breakthrough bleeding and/or spotting was si gnificantly higher only in the first 2 cycles in the patch group, but the i ncidence of breakthrough bleeding alone was comparable between treatments i n all cycles. The mean proportion of participants' cycles with perfect comp liance was 88.2% (811 total participants, 5141 total cycles) with the patch and 77.7% (605 total participants, 4134 total cycles) with the OC (P <.001 ). Only 1.8% (300/16673) of patches completely detached. Both treatments we re similarly well tolerated; however, application site reactions, breast di scomfort, and dysmenorrhea were significantly more common in the patch grou p. Conclusion The contraceptive patch is comparable to a combination OC in con traceptive efficacy and cycle control. Compliance was better with the weekl y contraceptive patch than with the OC.