Abstracts

Rationale: Rufinamide has been approved by FDA for the adjunctive treatment of seizures associated with Lennox-Gastaut Syndrome in children 4 years and older and adults since 2008. The objective of this study was to examine rufinamide dosing patterns in commercially insured patients. Methods: Using administrative claims from the MarketScan Commercial Database, patients initiating rufinamide (index event) during 11/1/2008 - 9/30/2010 with at least 6 months pre- and post-index eligibility were selected. Patients may have received other antiepileptic drugs (AEDs) during this observation period. Demographics and clinical characteristics, including AED therapies, were measured in the 6-month pre-index period. Rufinamide dosing was measured in patients with a minimum of 3 rufinamide prescription claims during the post-index period until discontinuation of rufinamide, end of the patient's available data, or March 31, 2011. Rufinamide daily dose was computed per prescription claim as the total amount dispensed divided by the days of supply. The initial dose, modal (most common) dose, time to modal dose, maximum dose, and last dose were analyzed by age category. Discontinuation, defined when there was a prescription supply gap of at least 30 days, was modeled using Cox proportional hazards analysis. Results: A total of 661 patients were included in the study, with mean age 16.9 years (Ys) (13.8% ≤5Ys, 27.0% 6-11Ys, 35.6% 12-21Ys, 23.8% >21Ys), 53% male, and mean follow-up duration of 491 [SD 180] days. Pre-index comorbidities included mental retardation (14.1%), developmental delay (19.7%), and growth delays (18.0%). In the 90 days prior to rufinamide, 29.6% of patients were receiving 2 AEDs and 50.8% were receiving 3 or more AEDs. The most common pre-index AEDs were lamotrigine (33.1%), levetiracetam (32.7%), and divalproex sodium (28.6%). However, no specific AED combination was used in more than 2% of patients in the pre-index period. Daily doses of rufinamide are shown in Table 1. The median days to modal dose were 33.0 [IQR 120] with mean days 72.4 [SD 91.6]. Cox regression analysis showed a hazard ratio of 0.593 for discontinuation of rufinamide when time to modal dose exceeded 30 days (p<0.001). Conclusions: Rufinamide was initiated in commercially insured patients who were on highly individualized AED polytherapy regimens and had commonly received 3 or more AEDs. Dosing of rufinamide varied by age category, and for adult patients, the observed daily dose appeared to be lower than the recommended maximum dose of 3200 milligrams. The data suggest the hypothesis that time to modal dose exceeding 30 days may be associated with a lower likelihood of discontinuation.