Longitudinal Australian trends in the initiation of valproate medication among women of reproductive age and concurrent use of prescription contraceptives

BACKGROUND: Awareness of the risks of prescribing valproate to girls and women of childbearing potential has increased, with some countries strongly restricting prescribing and requiring pregnancy prevention plans. OBJECTIVES: To explore changes in valproate dispensing patterns and the proportion of women covered by prescription contraceptives, especially long-acting forms, in Australia. DESIGN: Population-based cohort study using routinely collected government data on dispensed medications. METHODS: We analysed a 10% random sample of Australian Pharmaceutical Benefits Scheme (PBS) dispensing data for women aged 15-49 years. We calculated the annual rate of initiating valproate and alternative anti-seizure medications. We assessed what proportion of women were covered by long-acting or other PBS prescription contraception at treatment commencement. RESULTS: Between 2013 and 2021, overall valproate initiation declined substantially (from 2.06 to 0.75 per 1000 women per annum), compensated by a rise in the initiation of alternative anti-seizure medications. This reflected a decline in valproate initiated as a first-line treatment, with valproate initiated as a second-line treatment remaining stable. For women initiating valproate, contraception coverage by an intrauterine device or implant increased from 16% in 2013 to 22% in 2021. In 2021, no coverage by PBS prescription contraceptives occurred in 69% of women initiating valproate and 68% of women initiating alternative anti-seizure medications. CONCLUSIONS: A decline in valproate prescribing has occurred in Australia. At the time treatment commenced, the great majority of women dispensed valproate were not covered by any form of PBS prescription contraceptive, which is of concern.