Rationale and Background:
Vaproic acid/valproate-containing medicine (VPA) are first-line treatment for generalised tonic-clonic seizures (epilepsy) and adjunctive therapies in other types of seizures. They are also used as second-line treatments or adjuncts for the treatment of bipolar disorder, and for migraine prevention. Valproic acid is a teratogen, with prenatal exposure carrying a substantial risk of neurodevelopmental impairment and congenital malformations in the child. Therefore, its use in women of childbearing age is restricted to prevent valproate exposure during conception and pregnancy.
The European Medicines Agency (EMA) has issued risk minimisation measures in 2014 and 2018 including a compulsory pregnancy prevention program. Timely information on the use of VPA in young women across Europe is important.
Research question and Objectives:
The objectives of this study are
1. To estimate the population-level use (incidence rate and prevalence) of VPA in women between 12 and 55 years of age
2. To characterise patient-level VPA use in women between 12 and 55 years of age initiating treatment with VPA.
Research Methods:
Study design
• Population level cohort study (Objective 1, Population-level VPA utilisation)
• New user cohort study (Objective 2, Patient-level VPA utilisation)
Population:
Population-level utilisation of VPA and alternative treatments: All women aged between 12 years and =55 years between 01/01/2010 and 31/12/2022, with at least 365 days of prior history before the day they become eligible for study inclusion (study period: 2009-2022 including 1 year of previous data). For incidence, anyone with prior use of VPA will be excluded from the analysis.
Patient-level VPA utilisation: New users of VPA in the period between 01/01/2010 and 31/12/2021 (or latest date available), with at least 365 days of visibility prior to the date of their first VPA prescription, and no used VPA in the previous 365 days.
Variables
Drug of interest: Valproic acid, Sodium valproate, Magnesium valproate, Valproate semisodium and Valpromide
Alternative treatments: Carbamazepine, Phenobarbital, Phenytoin, Primidone, Clobazam, Clonazepam, Eslicarbazepine acetate, Lamotrigine, Oxcarbazepine, Perampanel, Rufinamide, Topiramate, Zonisamide, Brivaracetam, Ethosuximide, Gabapentin, Lacosamide, Levetiracetam, Pregabalin, Tiagabine, Vigabatrin, Lithium, Quetiapine, Olanzapine, Lamotrigine, Propranolol, Metoprolol, Atenolol, Nadolol, Timolol, Bisprolol, Topiramate, Amitriptyline, Flunarizine, Pizotifen, Clonidine
Data sources
1. Integrated Primary Care Information Project (IPCI), The Netherlands
2. Sistema d’Informació per al Desenvolupament de la Investigació en Atenció Primària (SIDIAP), Spain
3. IQVIA Longitudinal Patient Database Belgium (IQVIA LPD Belgium), Belgium
4. IQVIA Disease Analyzer Germany (IQVIA DA Germany), Germany
5. Hospital District of Helsinki and Uusimaa (HUS), Finland
6. Clinical Practice Research Datalink GOLD (CPRD GOLD), United Kingdom
Sample size
No sample size has been calculated. Feasibility counts have been generated in the general population in each databases.
Data analyses
For all analyses a minimum cell count of 5 will be used when reporting results, with any smaller counts obscured.
Population-level VPA utilisation: Annual period prevalence of VPA use and alternative treatments will be estimated, as will annual incidence rates per 100,000 person years.
Patient-level VPA utilisation: Large-scale patient-level characterisation will be conducted. Medical History will be assessed for anytime – 366 days before index date, for 365 to 31 days before index date, for 30 to 1 day before index date, and at index date. Medication use will be reported for 365 to 31 days before index date , for 30 to 1 day before index date, and at index date. Frequency of indication, namely epilepsy, bipolar disorder and migraine at index date will be assessed. Initial dose/strength and treatment duration will be estimated and the minimum, p25, median, p75, and maximum will be provided.