Abstracts

Rationale: Some currently prescribed AEDs (eg, carbamazepine, phenytoin, and phenobarbital) induce hepatic enzymatic activity and may increase risk of long-term adverse consequences (eg, osteoporosis, cardiovascular risk) potentially leading to increased healthcare expenditure. We compared direct healthcare costs associated with the prescription of EIAEDs and nEAAEDs in the UK.Methods: The Clinical Practice Research Datalink (CPRD) of UK primary care medical records, linked to Hospital Episode Statistics data, was used to select patients with epilepsy prescribed an EIAED or nEAAED between January 2001 and December 2010 (index) after ≥1 year without AEDs (baseline). Patients were followed-up until treatment failure or censoring (Fig 1). Propensity score matching was used to reduce the effects of confounding factors (age, gender, epilepsy-related variables, comorbidities, non-AED medications, healthcare cost) between the 2 cohorts. Key outcomes were time to treatment failure (end of last own-cohort AED or start of ex-cohort AED) and direct healthcare cost (cost of drugs; primary care consultations; accident and emergency visits; outpatient referrals and procedures; and hospitalizations, in 2014 £ values). Categorical and continuous variables were summarized descriptively; time to treatment failure was analyzed using Kaplan-Meier (K-M) survival methods.Results: The initial population consisted of 4,889 patients. At baseline, the EIAED cohort was older (54.2y vs 45.9y), more likely to be male (54.8% vs 37.3%), have a diagnosis of partial epilepsy (17% vs 14%), and had higher healthcare resource use than the nEAAED cohort. After matching, the 2 cohorts (n=951 each) were similar on all selected confounders. The most commonly prescribed EIAED and nEAAED were carbamazepine (73%) and lamotrigine (67%), respectively. The K-M estimated median time to treatment failure for the EIAED cohort was 468 days vs 1194 days for the nEAAED cohort. Over the entire follow-up period, mean (median) monthly direct healthcare cost was estimated at £495 (£229) and £432 (£188) with EIAED and nEAAED treatment, respectively. Median baseline direct healthcare cost was ~£2,300 for both groups; direct costs were £2,021 (EIAED, n=467) and £1,881 (nEAAED, n=576) in the first year post-index and continued to drop in year 2 (Fig 2). In later years, costs were increasingly larger for patients remaining in the EIAED cohort and smaller for the nEAAED cohort.Conclusions: These data suggest that in the UK, EIAEDs are prescribed to older patients with higher baseline healthcare resource use. In matched cohorts, time to treatment failure was shorter for EIAED than nEAAED. Even though EIAEDs are generic and may be less costly drugs, the average total direct healthcare cost was found to be larger than for nEAAEDs. UCB Pharma-sponsored