Abstracts

Rationale: Maintenance of an optimal antiepileptic drug (AED) regimen remains challenging in epilepsy patients. Suboptimal adherence to AEDs results in increased risk of seizures, injury, hospitalization and mortality. In order to optimize medical therapy in epilepsy patients, it is important to identify patient and AED characteristics which affect adherence. Methods: Literature review of the Cochrane Library, MEDLINE, EMBASE and CINAHL databases. After screening, 23 studies which assessed AED adherence in epilepsy patients were identified. Results: Rates of non-adherence ranged from 25-79%. Multiple measures of adherence were used, limiting direct comparison of studies. Variability in adherence rates was affected by demographic group, monotherapy versus polytherapy, AED dosing schedule and AED side effects. Elderly patients consistently showed lower adherence rates due to causes including cognitive or language impairment, misconceptions regarding side effects, and AED cost, with a robust negative relationship between out-of-pocket prescription costs and adherence in elderly epileptic patients. In children, adherence rates were positively correlated with married status of parents and higher socioeconomic status, and no association was found between adherence and seizure severity/frequency across multiple studies. Adolescents showed poor adherence rates secondary to social stigma, lack of social support, and the transition of medication responsibility from parent to adolescent. Compared to Caucasians, decreased adherence rates were demonstrated in low-income ethnic minorities and African Americans. In third-world countries, adherence is adversely affected by inadequate education, lack of access to affordable AEDs and cultural beliefs. Newer AEDs generally result in better adherence due to fewer side effects and decreased drug interaction potential, although one study showed that adherence was associated with patient satisfaction with therapy efficacy despite AED side effect profile. Less frequent dosing has been associated with improved adherence in most studies, although patients on monotherapy may also demonstrate poorer adherence than patients on polytherapy. This may be due to the fact that polytherapy patients have poorly controlled seizures, which provides a greater impetus to maintain good adherence. Conclusions: Suboptimal adherence to AEDs among epilepsy patients has serious consequences, including increased morbidity, mortality, and healthcare cost utilization. Adherence is affected by features unique to each demographic group, as well as to AED characteristics including monotherapy versus polytherapy, side effect profile, and dosing schedule. Strategies for improved adherence should account for the individual characteristics of each patient. However, there is a significant need for further studies to better understand non-adherence patterns among patients, and to develop effective interventions in order to optimize medical management.