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

Abstract

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% (300/16 673) 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.