Comparing healthcare cost associated with the use of enzyme-inducing and non-enzyme active antiepileptic drugs in elderly patients with epilepsy in the UK: a long-term retrospective, matched cohort study.

BACKGROUND: In elderly patients (≥65 years of age) with epilepsy who take medications for comorbid conditions, some antiepileptic drugs (AEDs) may alter the metabolism of other treatments and increase the risk of adverse consequences and healthcare utilisation. This analysis compares healthcare costs associated with enzyme-inducing AEDs (EIAEDs) and non-enzyme active AEDs (nEAAEDs) use in elderly patients with epilepsy. METHODS: This retrospective matched cohort study used the Clinical Practice Research Datalink (CPRD) of UK primary care medical records, linked to the Hospital Episode Statistics (HES) database. Selected patients with epilepsy were ≥ 65 years and prescribed an EIAED or nEAAED between 2001 and 2010 (index) after ≥1 year without AEDs (baseline) and followed until the first occurrence of the following: end of HES data coverage, end of GP registration, or death; practice's up-to-standard status or addition of an AED belonging to another cohort or discontinuation of the last AED of that cohort. Propensity score matching reduced confounding factor effects between cohorts. Key outcomes included time to cohort treatment failure, time to index AED treatment failure, and direct healthcare costs in 2014 Pound Sterling (£) values. RESULTS: Overall, 1425 elderly patients were included: 964 with EIAEDs and 461 with nEAAEDs. At baseline, the EIAED cohort was older (mean age, 76.2 vs. 75.1 years) and a higher proportion were male. Baseline direct healthcare costs were similar. After matching (n = 210 each), and over the entire follow-up period, median monthly direct healthcare costs were higher for patients taking EIAEDs than nEAAEDs (£403 vs. £317; p = 0.0150, Mann-Whitney U). Costs were higher for patients remaining in the EIAED cohort after 3 follow-up years. The median time to cohort treatment failure for the EIAED cohort was 1110 days vs. 1175 days for the nEAAED cohort. CONCLUSION: Newly treated elderly patients with epilepsy were more likely to be prescribed EIAEDs than nEAAEDs. In matched cohorts, elderly patients with epilepsy treated with EIAEDs had higher average total direct and epilepsy-related healthcare costs than nEAAED-treated patients; this difference was greater than previously reported in the overall adult population. Changing treatment practices could improve patient care and reduce costs.

Health care cost associated with the use of enzyme-inducing and non-enzyme-active antiepileptic drugs in the UK: a long-term retrospective matched cohort study.

BACKGROUND: Some antiepileptic drugs (AEDs) induce expression of hepatic enzymes. This can contribute to comorbidities via interference with metabolic pathways and concomitant drug metabolization, thereby increasing the likelihood of health care interventions. Using medical records, we compared the direct health care cost in patients initiating epilepsy therapy with enzyme-inducing AEDs (EIAEDs) vs non-enzyme-active AEDs (nEAAEDs) over up to 12 years. METHODS: Patients with untreated epilepsy were indexed in the UK Clinical Practice Research Datalink and Hospital Episode Statistics database when prescribed a new EIAED or nEAAED between January 2001 and December 2010. Propensity score matching reduced confounding factors between cohorts. Patients were followed until cohort treatment failure or data cut-off. The primary outcome was the median standardized monthly direct health care cost during follow-up in 2014 £GBP, calculated using published reference costs and compared using a Mann-Whitney U test. RESULTS: The unmatched EIAED cohort (n = 2752) was older (54 vs 46 years), more likely to be male, had more comorbidities, and higher health care resource use/cost during the 1-year pre-index period (median £3014 vs £2516) than the nEAAED cohort (n = 2,137). The most common index EIAED and nEAAED were carbamazepine (63.3%) and lamotrigine (58.0%), respectively. After matching, cohorts had similar features (n = 951 each). Over up to 12 years of follow-up, the median standardized monthly direct health care cost was £229 for the EIAED and £188 for the nEAAED cohorts (p = 0.0091). The median cost was higher for the EIAED cohort in every year of follow-up. In the two cohorts, 25.1% and 20.1% of total mean cost during follow-up was epilepsy-related, with approximately 4.6% and 3.0% for AED acquisition, respectively. The median time to cohort treatment failure was shorter in the matched EIAED cohort (468 vs 1194 days). CONCLUSIONS: Patients in the UK who initiated epilepsy therapy with an EIAED appeared to be at higher risk of complications associated with enzyme induction. In long-term matched cohort analyses, the median total direct health care cost associated with EIAED therapy was higher than with nEAAEDs. Changing current treatment practices could potentially improve patient outcomes and reduce costs.