Trends of utilization of antiepileptic drugs among pregnant women in Manitoba Canada. A 20-year population study

Abstract

Studies from Canada and globally have shown an increase in antiepileptic drug (AEDs) use in the past decade. This could be attributed to the fact that AEDs are being used more for off-label indications or a change in intensity of treatment. Identifying the impact of such increase among vulnerable groups, such as pregnant women, is imperative because pregnant women may have different utilization patterns than the general population. This study examines time-trends of utilization of AED therapies among pregnant women in Manitoba, Canada. This study is a population-based cohort study using administrative health data from the province of Manitoba. Pregnancies between 1995 and 2018 were included. Four groups of pregnant women were created based on AEDs exposure and epilepsy diagnosis. Trend analysis for change over time was conducted using linear regression. Out of 273,492 pregnancies identified, 812 (0.3%) had epilepsy diagnosis and were exposed to AEDs, 963 (0.35%) had an epilepsy diagnosis and were unexposed, 2,742 (1%) were exposed to AEDs and did not have epilepsy diagnosis, and 268,975 (98.35%) were not exposed to AEDs and did not have epilepsy diagnosis. Overall, the number of pregnancies exposed to AEDs increased significantly from 0.56% in 1997 to 2.21% in 2018 (p<0.0001). No significant change was observed in the exposure to AEDs among women with epilepsy (from 0.37% in 1997 to 0.36% in 2018, p=0.24). In contrast, the percentage of AEDs use among pregnant women without epilepsy increased significantly from 0.19% in 1997 to 1.85% in 2018 (p<0.0001). Over the 20 years of the study, carbamazepine was the most used AED among pregnant women with epilepsy (28.07%), followed by lamotrigine (18.88%), phenytoin (17.08%) and valproic acid (10.79%). There were no major shifts in the use of AEDs observed among women with epilepsy over the 20-year study period. Therefore, concerns about an increased use of AEDs, and reasons for the use, among pregnant women in Manitoba driven by indications other than epilepsy require additional research to better inform prescribers and policymakers.