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 increases 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 treatment 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 pregnancies/100 person-years of use) and life-table estimates of the probability of pregnancy were calculated. Cycle control, compliance, patch adhesion, and adverse events were also assessed. Results 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 (P=.57 and .80, respectively), The incidence of breakthrough bleeding and/or spotting was significantly higher only in the first 2 cycles in the patch group, but the incidence of breakthrough bleeding alone was comparable between treatments in all cycles. The mean proportion of participants' cycles with perfect compliance 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 were similarly well tolerated; however, application site reactions, breast discomfort, and dysmenorrhea were significantly more common in the patch group. Conclusion The contraceptive patch is comparable to a combination OC in contraceptive efficacy and cycle control. Compliance was better with the weekly contraceptive patch than with the OC.