Abstracts

Successful long-term management of epilepsy depends on patient compliance with antiepileptic drug (AED) regimens. Noncompliance resulting in suboptimal seizure control may increase healthcare costs. Noncompliance can also be a marker of patient satisfaction with therapy. We used refill data from a national managed care database of medical and pharmacy claims to assess patient compliance with phenytoin (PHT), carbamazepine (CBZ), valproate (VPA), and topiramate (TPM). Data for patients with epilepsy, identified by ICD-9 codes, were collected from a database containing claims from 57 managed care health plans covering 33 million patients, providing a nationally representative sample. For each AED, prescription activity during a 1 yr period was used to calculate the [ldquo]AED compliance ratio[rdquo] based on days of medication possession -- ie, total days for which AED had been prescribed/filled divided by days between first detected prescription and last prescription for that AED during 1-yr follow-up. Assumptions with this method are that 1) patients continued AED therapy throughout follow-up period and 2) all AEDs prescribed were consumed. Patients with ratio [ge]0.80 were deemed compliant. A logistic regression model quantified differences across AEDs, controlling for age, gender, comorbidities and combination therapy. A total of 20,774 patients with epilepsy and [ge]1 yr data following an initial prescription for PHT, CBZ, VPA, or TPM between January 1, 1998 and July 30, 2003 were identified. 53% were male; mean (SD) patient age was 38.6 (12.7) yrs. The TPM cohort included significantly more women than men (58% vs. 46%, P[lt]0.0001). Compliance ratios: PHT, 0.78; CBZ, 0.78; VPA, 0.73; TPM, 0.82. Proportion of compliant patients: PHT, 63%; CBZ, 63%; VPA, 53%; TPM, 68%. Based on logistic regression model, TPM was associated with 30% greater likelihood of compliance ([ge]0.80) compared with other AEDs (Odds Ratio=1.30; P=0.002). Compliance with TPM was superior to that with PHT, CBZ, and VPA. Greater compliance suggests greater patient satisfaction with TPM therapy, with the potential for better outcomes in epilepsy. (Supported by Ortho-McNeil Pharmaceutical)