Prevalence Ratios for Unintended Pregnancy on Various Contraceptive Methods and AEDs in Women with Epilepsy: Interim Analysis from the Epilepsy Birth Control Registry (IN5-1.006)

Abstract

Objective: To determine the prevalence of unintended pregnancy associated with various contraceptive methods (CMs) and categories of antiepileptic drugs (AEDs) in women with epilepsy (WWE). Background Contraception requires special consideration in WWE because contraceptive hormones have reciprocal interactions with AEDs that may affect seizures and CM efficacy. The relative efficacy of CMs in WWE in the community, however, has received little systematic investigation. Design/Methods: These retrospective data come from the first 350 WWE in the community, 18-47 years old, who completed the Epilepsy Birth Control Registry web-based survey that collected demographic, reproductive, contraceptive, epilepsy and AED data. We calculated prevalence ratios (probability of unplanned pregnancy on method / probability of unplanned pregnancy not on method) for CMs used by the survey population. We carried out univariate ANOVA to determine whether AED category (enzyme inducing EIAED, glucuronidated [lamotrigine, valproate] GLUAED, non enzyme inducing NEIAED and no AED) was a predictor of hormonal v non-hormonal CM failure. Results: Unintended pregnancies occurred in 125 (85.6%) of the 146 women who had pregnancies. Of the 340 pregnancies, 63.2%, were unintended as compared to 49% in a general U.S. population survey of 7,643 women (p = .0001). Prevalence ratios for unplanned pregnancy on various CMs is presented in decreasing order: no contraception - 10.45, withdrawal - 4.20, male condom - 0.72, oral contraceptive - 0.41 and depomedroxyprogesterone - 0.40. Prevalence ratios for AED categories was EIAED - 2.88, no AED - 0.91, GLUAED - 0.32, NEIAED - 0.28. In this interim analysis, ANOVA did not find AED category to be a significant predictor of hormonal versus non-hormonal CM failure. Conclusions: Unintended pregnancy may be more common among WWE than in the general population. Both the CM type and AED category impact the prevalence ratios of unintended pregnancies in WWE. Supported by: Epilepsy Foundation. Disclosure: Dr. Herzog has nothing to disclose. Dr. Davis has received personal compensation for activities with Bayer Pharmaceuticals and Schering Plough as an advisory board member.Dr. Davis has received research support from Bayer Pharmaceuticals. Dr. Hauser has received personal compensation for activities with Pfizer Inc, Ovation Pharmaceuticals, Inc., Valeant Pharmaceuticals as consultant. Dr. Saporta has nothing to disclose. Dr. Cahill has nothing to disclose. Dr. Fowler has nothing to disclose.