Compared to nonhormonal contraception (NHC), hormonal contraception (HC) appears to pose a greater risk for increased seizure frequency in women with epilepsy, especially among those being treated with lamotrigine. This according to research presented at the 2019 American Epilepsy Society Annual Meeting, held December 6 to 10, in Baltimore, Maryland.

While retrospective survey evidence has suggested that women with epilepsy have an increased risk for greater seizure frequency while on HC compared to NHC, there is a need for large-scale prospective studies. As such, the Epilepsy Birth Control Registry (EBCR) gathered prospective data on the seizure frequency of 101 women with epilepsy aged 18 and 47 years who switched between HC (depomedroxyprogesterone, implanted progestin, vaginal ring, hormonal patch, or oral contraceptive pills) and NHC (no contraception, IUD, barrier, and withdrawal).

Data was recorded for the 3 months preceding and subsequent to change in contraceptive method. Interim analyses focused on risk ratio (RR) (>50% decrease or increase in seizure frequency) after change in contraceptive method, monthly seizure frequency changes before and after change in contraceptive method, and effect of anti-epileptic drug (AED) category (no AED, glucuronidated [lamotrigine], enzyme-inhibiting, non-enzyme inducing, enzyme-inducing, mixed) or AED change during the recording period.

Among women who changed contraceptive method from HC to NHC (n=63), there was a  greater risk for seizure decrease vs increase (49.2% vs 19.0%; RR, 2.58; 95% CI, 1.46-4.56; P =.001). Among those who switched from NHC to HC (n=38), a greater risk for seizure increase vs decrease was observed (44.7% vs 21.1%; RR, 2.13; 95% CI, 1.04-4.32; P =.0374). Change from HC to NHC was associated with an 81.9% decrease in monthly seizure frequency (0.447-0.081; P =.001). Conversely, change from NHC to HC was associated with a 302.0% increase in monthly seizure frequency (0.203- 0.816; P =.019).

Direction of change between HC and NHC was a significant predictor of seizure frequency change. The odds ratio for a decrease in seizure frequency relative to an increase in seizure frequency in women who switched from HC to NHC compared to those who switched from NHC to HC was 5.490 (1.878-16.044; P =.002). Investigators found the odds ratio elevated after adjusting for AED category and change, with a >50% change in frequency for seizures more likely to occur with lamotrigine. A change from NHC to HC had a RR of 4.00 (95% CI, 1.06-15.08; P =.04) for increased seizure frequency relative to decreased frequency.

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Investigators concluded, “The prospective interim findings of the effects of changes between HC and NHC on seizure frequency suggest that HC poses the greater risk for increased seizures especially for [women with epilepsy] on lamotrigine.”

Disclosure: This study was supported by Lundbeck. Please see the original reference for a full list of authors’ disclosures.

Reference

Herzog AG, MacEachern DB, Dost IS, Mandle HB. Hormonal versus non-hormonal contraception effects on seizure frequency: Prospective interim findings of the epilepsy birth control registry. Presented at: the American Epilepsy Society’s Annual Meeting; December 6-10, 2019; Baltimore, MD. Abstract 1.252