Impact of nonadherence to antiepileptic drugs on health care utilization and costs: Findings from the RANSOM study

Summary Purpose: To study the impact of nonadherence to antiepileptic drugs (AEDs) on health care utilization and direct medical costs in a Medicaid population. Methods: A retrospective cohort design was employed using state Medicaid claims data from Florida, Iowa, and New Jersey during the period from January 1997 to June 2006. Patients aged ≥18 years with one or more neurologist visit with an epilepsy diagnosis and two or more pharmacy claims for AEDs were included. Medication possession ratio (MPR) was used to evaluate AED adherence with MPR ≥ 0.80 considered adherent and