Abstracts

Rationale: Reciprocal interactions occur between some antiepileptic drugs (AEDs) and contraceptive hormones but we know little about their impact on seizures in the clinical setting. The purpose of this study is to determine whether there are changes in seizure frequency with hormonal contraception (HC) and if they vary by type of AED therapy and AED category in women with epilepsy (WWE). Methods: The data come from retrospective chart review analysis of 30 WWE, ages 18-47 years, seen in the Epilepsy Clinic at the University of Michigan who were taking contraceptive hormones in addition to anticonvulsant therapy. We looked at three categories of seizure outcomes: "improved", "worsened", or "no effect" as documented in patients' records in response to the question "Do you think your seizure frequency changed with the method of birth control?" The patients have been on HC for at least three months. We compared the seizure frequency stratified by: Type of anticonvulsive therapy: monotherapy or polytherapy; AED category in the monotherapy group: (EI-AED) enzyme inducing AED, (Glu-AED) glucuronidated AED, (NEI-AED) non EI-AED, (EInh-AED) enzyme inhibiting AED; and Type of hormonal contraception: combined (pills, patch), progestin based (pills, injection, implant, IUD), and estrogen based (pills, patch, cream) Results: 20 WWE were on polytherapy with 2 or more AEDs and 10 WWE were on monotherapy. In the monotherapy group 5 women were on NEI-AEDs and only small numbers of patients were on a different AED category. 12 WWE (40%) of the entire patient cohort were taking combined hormonal contraceptives, 13 WWE (43%) were on progestin-based contraceptives and 5 (17%) were on estrogen-based contraceptives. 75% of the WWE who were on polytherapy with AEDs and 80% of the WWE on AED monotherapy did not report change in their seizure frequency in relation to the HC. 20% of the patients who were either on polytherapy (most were on combination of Levetiracetam, Topamax, and Lamotrigine) or monotherapy (on NEI-AED) reported improved seizure control. Only 1 woman in the polytherapy group, who was on combination of Levetiracetam and Lamotrigine, had worsened seizure control. 69% of the WWE given progestin-based contraceptives and 75% of the WWE given combined contraceptives had unchanged seizure frequency. All patients on estrogen-based drug did not report effect on seizure control. 31% of the WWE on progestin preparation and 17% of the WWE on combined preparation had improved seizure control. Only 1 woman in the combined HC group reported worsened seizure control. Chi square and Fisher's exact statistical analyses were performed. None of the associations between seizures outcomes and type of AED therapy and hormonal contraceptive reached statistical significance (p=0.4-1.0). Conclusions: Our retrospective chart review analysis showed that the majority of WWE, 77% (N=23), reported no effect on seizure control in relation to hormonal preparations regardless of the AED therapy. When the outcomes were stratified by type of hormonal contraceptive, 77% (N=23) of the cohort did not report changes. 20% (N=6) of all women had improved seizure control and most of them (N=4) were on progestin-based contraceptive, which is in agreement with the literature and known anticonvulsive properties of progesterone. No reliable conclusions can be drawn regarding the impact of different AEDs on seizure control in light of HC due to the small number of patients in the monotherapy group. Overall, there was no correlation between types of hormonal contraception (progestin-based, combined, and estrogen-based) and seizure frequency in relation to AED polytherapy or monotherapy, and AED type. Statistical significance was not achieved due to small sample size. Funding: None