Is Evra, a transdermal, once-weekly, combined contraceptive patch
cost-effective compared to combined oral contraceptives?
F.A. Sonnenberg (1), C.G. Hagerty (1), M.J. Price (2), C. Neslusan (3)
UMDNJ Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA
(1); Janssen-Cilag Ltd, High Wycombe, UK (2); Johnson & Johnson
Pharmaceutical Services, Raritan, New Jersey, USA (3)
Introduction: Observational studies have demonstrated that real world
failure rates with COCs are considerably higher than observed in clinical trials
because of inappropriate use and poor compliance. New methods that improve
convenience and compliance are needed to reduce unwanted pregnancies. In
clinical trials Evra, a once-weekly, transdermal, combined contraceptive patch
was as effective as COCs with perfect use. Studies also showed that Evra users
had better compliance than COC users. In order to predict unplanned pregnancies
expected with Evra compared to COCs and to evaluate the cost-effectiveness of
these two methods with typical use, a cost-effectiveness model was developed.
Design & Methods: The Contraceptive Choice Model (CCM) was
developed to evaluate the net costs and outcomes associated with contraceptive
methods. Costs associated with method acquisition and pregnancy (to delivery or
termination) are costed from a UK NHS perspective. The model calculated the
number of unintended pregnancies expected with typical use of each method. It is
assumed that Evra and COCs have the same efficacy with perfect use, but that
real world effectiveness of Evra would be better than with COCs due to improved
compliance. The model uses the pooled phase III clinical trial results, which
showed that older women were more compliant with COCs than younger women.
Perfect cycles varied from 76% in<20s to 90% in the 40+ age group. With Evra, compliance was consistently high varying by only 2% from 90% in the<20s to 92% in the 40+ group. The annual probability of pregnancy with Evra was calculated as the annual probability of pregnancy with OCs (adapted from Jones & Forrest, Family Planning Perspectives 1989; 21:103–109) multiplied by the ratio of imperfect cycles for Evra versus OCs. To calculate cost-effectiveness, we ran a simulation of 100,000 women for each method, based on the demographic characteristics of the UK.
Results: The model shows that Evra prevents more unplanned pregnancy
in all age groups than OCs. Evra has the greatest costeffectiveness advantage in
the <20 age group with a 50% reduction in unplanned pregnancies, at a lower cost to the NHS. In the 20–24 year age group, the model shows that Evra reduces unwanted pregnancies by 40% at an additional NHS cost of 26 per women per year. Evra’s cost-effectiveness was less favourable in older women who were more compliant with COCs.
Conclusions: Evra is a cost-effective method in women who are likely
to be poorly compliant with COCs. In the phase III clinical trials, women aged
<20 were more likely to be non-compliant and in this age group, Evra prevented more unplanned pregnancies at a lower NHS cost compared to COCs. Other risk factors for poor compliance include prior OC failure and lack of a daily routine.