Abstracts

Rationale: Poor medication compliance is widespread and problematic in epilepsy, due in part to complex dosing regimens for some antiepileptic drugs (AEDs). AED noncompliance leads to higher rates of seizure recurrence and associated increases in health care utilization and costs. The issue of treatment noncompliance in elderly patients with epilepsy and its cost implications for commercial third party payers has not been widely investigated.Methods: Retrospective insurance claims of managed care enrollees from the Integrated Health Care Information Services database (1/1/00 – 6/31/06) were analyzed. Inclusion criteria were: age 65+, at least one diagnosis of epilepsy (ICD-9 345.xx) or non-febrile convulsions (ICD-9 780.3, 780.39) by a neurologist, at least 2 AED prescriptions, and continuous health plan enrollment for at least 6 months prior to and at least 12 months following AED initiation. Compliance was evaluated using the medication possession ratio (MPR), defined as the ratio of total AED days supplied to the number of days between first and last AED refill. Patients with an MPR of less than 0.8 were classified as noncompliant. Multivariate regression was used to assess the incremental effect of noncompliance on annualized all-cause health care costs, controlling for patient demographics, Charlson Comorbidity Index (CCI), follow-up duration (minimum of 12 months), and AED monotherapy initiation.Results: Among patients meeting all inclusion criteria (N=1,278), 50.2% were female, mean age was 73 years (SD=4.5), mean CCI was 2.5 (SD=2.3), mean follow-up duration was 34 months (SD=17.5), and 95% initiated monotherapy. Phenytoin was the most commonly prescribed AED (43.5% of all prescriptions observed), with gabapentin (18.5%) and valproate (9.1%) the next most frequently seen. The majority (65.1%) of AED prescriptions were for older agents. Mean MPR for overall AED therapy was 0.76 (SD=0.28) and 40.7% of patients were noncompliant. Noncompliance was associated with an increase in annual per patient hospital stays, days in hospital, emergency department visits, and physician office visits (all P<0.005). AED noncompliance increased annual total healthcare costs by $2,421 (P=0.012) per patient. For specific cost sectors, noncompliance was associated with increases of $893 (P=0.001), $136 (P=0.001), and $1,679 (P=0.010) per patient for inpatient, emergency department, and other ancillary care costs, respectively. Annual outpatient costs were not significantly affected by noncompliance (+$337; P=0.1203). As expected, AED noncompliance was associated with a substantial decrease in annual costs for AEDs (-$386; P<0.001) and other prescription drugs (-$485; P=0.070).Conclusions: Compliance with AEDs among elderly epilepsy patients is suboptimal. A large and positive net effect of AED noncompliance on total health care costs remained despite lower costs for AEDs and other prescription drugs as a result of reduced drug intake. Efforts to promote AED compliance among elderly patients may lead to cost savings for managed care systems.