Abstracts

Rationale: Some reproductive steroids have neuroactive properties that affect neuronal excitability and seizure thresholds but little is known about the effects of hormonal contraception (HC) on seizures in women with epilepsy (WWE). The purpose of this study is to determine whether HC differs from non-HC (NHC) in its effects on seizure frequency in WWE in the community.Methods: The Epilepsy Birth Control Registry (EBCR) is a web-based survey that gathers demographic, epilepsy, AED, contraceptive & reproductive data from WWE in the community. These retrospective data come from 2712 contraceptive experiences reported by 1144 WWE, ages 18-47 years, who completed the survey. Data are the frequencies of ""increase,"" ""decrease,"" and ""no change"" responses to the question “Do you think that this method of birth control changed how often you had seizures?” We compared proportions of WWE who reported seizure change on the broad class of HC (combined or progestin-only pills, hormonal patch, vaginal ring, depomedroxyprogesterone [DMPA], implanted hormones) vs NHC (withdrawal, male & female condom, copper & progestin IUD, tubal ligation) using Χ2 analysis. Combinations were designated as HC if they included the use of systemic hormones. We compared the relative risks (RRs) of reports of seizure increase and decrease on HC vs NHC as well as on more specific contraceptive categories (withdrawal, barrier, hormonal [subcategories: oral, non-oral, combined, progestin-only], IUD, tubal ligation).Results: While the majority of WWE report no change in seizure frequency with the use of HC (933/1300, 71.8%) and NHC (1280/1412, 90.7%), more WWE report a change on HC than NHC (28.2% vs 9.3%, Χ2 = 159.48, df = 1, p <0.0001). RR for seizure increase on HC (243/1300, 18.7%) vs NHC (59/1412, 4.2%) is 4.47 [95% CI = 3.40-5.89, p <0.0001]. Table 1 shows frequencies of reports of seizure increase and decrease by categories of contraception. RRs for seizure increase by individual contraceptive category are presented in Fig. 1. Only the hormonal category carries a significantly greater RR for seizure increase than barrier which has the lowest rate at 3.0% (RR = 6.75 [4.35-10.45], p = <0.0001). In comparison to combined oral contraceptive pills (OCP), the most frequently used method, both hormonal patch (RR = 1.68, 95% CI = 1.11-2.56, p = 0.01) and progestin-only OCP (RR = 1.62, 95% CI = 1.05-2.49, p = 0.03) have greater RRs for seizure increase. RR for seizure decrease on HC (124/1300, 9.5%) vs NHC (73/1412, 5.2%) is 1.85 [95% CI = 1.40-2.44, p <0.0001]. DMPA (35/200, 17.5%) is the only HC method with greater RR for seizure decrease than combined OCP (57/635, 9.0%): RR = 1.95, 95% CI = 1.32-2.88, p = 0.0008).Conclusions: The EBCR retrospective survey findings show that the majority of WWE report no change in seizure frequency with the use of HC and NHC. However, more WWE experience change on HC than NHC. RR for seizure increase is greater with HC than NHC. RR is greater with hormonal patch and progestin only OCP than with combined OCP. RR for seizure decrease is greater with DMPA than with combined OCP.