Contraceptive and Enzyme-Inducing Antiseizure Medication Coprescription Among US Medicaid Beneficiaries With Epilepsy.

Abstract

Background and objectives: People with epilepsy of child-bearing potential (PWECP) require access to highly effective contraception, yet many antiseizure medications (ASMs) can reduce the effectiveness of some hormonal methods by inducing hepatic enzymes. In this retrospective cohort study, we aimed to identify the proportion of PWECP prescribed a susceptible hormonal contraceptive method who were concurrently prescribed an interacting ASM and patient characteristics associated with coprescription.

Methods: We obtained Medicaid claims data from 2016 to 2021 for female beneficiaries and defined a cohort of people with epilepsy on ASMs prescribed at least 1 method of hormonal contraception susceptible to hepatic enzyme induction. Using prescription fill dates and contraceptive procedure dates, we identified periods of inducing ASM and susceptible contraceptive overlap lasting at least 14 days. We used descriptive statistics to calculate the proportion experiencing overlap and median days of overlap. We used logistic regression to identify associated patient characteristics with any 14-day period of overlap and binominal regression to identify characteristics associated with greater proportion of overlap days.

Results: Our cohort included 110,976 PWECP (median age 24 [interquartile range 18-30] years, 54.8% White non-Hispanic). Of those, 21,923 were prescribed a susceptible contraceptive method from 2018 to 2021. In that group, 7,154 (32.6%) had at least a 14-day period of overlap with an enzyme-inducing ASM. The median days of overlap for this group were 218 days (interquartile range 74-511). Patient characteristics associated with both any period of overlap and longer periods of overlap included intellectual disability (any overlap: adjusted odds ratio [aOR] 2.33, 95% CI 2.19-2.48; longer overlap: 2.27, 95% CI 2.05-2.53), drug-resistant epilepsy (any overlap: aOR 1.73, 95% CI 1.62-1.84; longer overlap: 1.27, 95% CI 1.14-1.41), and age older than 35 years compared with 19-34 years (any overlap: 1.45, 95% CI 1.32-1.59; longer overlap: 1.51, 95% CI 1.29-1.75).

Discussion: Drug interactions with ASMs leading to reduced contraceptive effectiveness are common among PWECP prescribed susceptible hormonal contraception. Certain populations, including those with intellectual disability, drug-resistant epilepsy, or age older than 35 years, were more likely to experience these drug interactions. Limitations include that our data set lacks information on adherence, counseling, pregnancy intentions, sexual orientation and activity, and barrier use.