Abstracts

Partial epilepsy is typically managed by monotherapy with anti-epileptic drugs (AEDs). Patients who are refractory to the initial regimen, however, may be switched to monotherapy with another AED or to combination therapy involving the initial AED plus a second AED. The purpose of this study was to understand the economic costs of these refractory patients and to compare the costs of two alternative regimens: (1) switching refractory patients to oxcarbazepine monotherapy (OXC monotherapy), and (2) augmenting to combination therapy (AED add-on). Adult patients receiving AED monotherapy with carbamazepine, phenytoin, or valproic acid between January 1, 2000 and March 30, 2004 were identified in a managed care administrative claims database. The medical and pharmacy history of these patients was analyzed from 6 months prior to treatment change to either OXC monotherapy or augmentation (AED add-on) through12 months after treatment change. Total health care resource utilization and associated costs were compared within each cohort pre- and post-change and between cohorts, with statistical differences tested using Wilcoxon rank sum tests. Multivariate econometric analyses examined the impact of patient age, gender, geographic location, Charlson comorbidity score, and specific comorbidities. Demographic and clinical characteristics were statistically similar between the OXC monotherapy cohort (n=259) and the AED add-on cohort (n=795). Annual treatment costs rose for both groups during the post-failure period ([italic]P[/italic][lt]0.01). The mean increase in the cost of overall care was statistically significantly lower for OXC monotherapy patients than AED add-on patients ($898 (SD $19,812) vs. $2,064 (SD $19,505), p [lt] 0.05), and the AED add-on cohort had statistically significantly more ER visits (OR=1.49, p [lt]0.05). These results provide a real-world view of the per-patient medical cost to care for patients with partial epilepsy in the United States. Patients with partial epilepsy who are initiated on standard AED monotherapy with carbamazepine, phenytoin, or valproic acid and then switched to OXC monotherapy have significantly lower cost outcomes than patients who receive AEDs as combination therapy. (Supported by Novartis Pharmaceuticals Corporation.)