Abstracts

Rationale: Numerous medications are currently available for the treatment of epilepsy. However, variability in patient response and tolerance contribute to complex disease management. Data demonstrating how antiepileptic drugs (AEDs) are being used is necessary to better understand the diversity of epilepsy treatment in Canada. This observational study followed a Canadian cohort of drug naïve epilepsy patients over 3 years to evaluate the treatment pathway of AEDs. Methods: A national claims database, IMS Brogan, was utilized to identify a cohort of epilepsy patients, ≥ 18 years, followed from 2008 to 2011. A pre-specified list of inclusion criteria, driven largely by medication history and prescriber's specialty, over the study period, was used to select the epilepsy patient cohort. In order to track up to 5 lines of therapy over 3 years, patients must have been active in their insurance plan throughout the study, and had their first claim for an AED between 2007 and 2008. Changes were grouped into 3 categories: addition of a new medication, removal of existing medication or switch to a different medication. If a removal occurred within 90 days of an addition, the change in treatment was categorized as a switch as the overlapping treatment is necessary for up and down titration. Details of all lines of therapy, including mono versus combination treatments, and the average time to each change, were assessed over the study. Results: A treatment naïve cohort of 3600 epilepsy patients was identified and followed over 3 years. Of these patients, 2736 (76%) progressed to 2nd line therapy, 2016 (56%) to 3rd, 1188 (33%) to 4th and 576 (16%) to 5th. The average days to change in treatment were 300, 271, 232, and 212 for lines 2 through 5, respectively. First line therapy was largely made up of patients on monotherapy (91%), with the majority taking carbamazepine (28%) or phenytoin (22%). A reduced 60% were on monotherapy by 5th line, driven by clonazapam (29%), valproic acid (15%) and gabapentin (11%). Of the 2736 patients who progressed to the 2nd line, 47% added, 49% switched and 4% reduced a therapy. In contrast, of the 576 patients who progressed to 5th line, 20% added, 16% switched, and 64% removed a therapy. Conclusions: Much of the epilepsy cohort progressed through multiple lines of therapy over 3 years. As lines of therapy increased, a reduction was observed in average days to change and monotherapy use. More variability in treatment was observed in later therapy. Additions and switches were common in earlier therapy, whereas, removals were more frequent later. The cohort was limited to the drug utilization inclusion criteria. Out-of-pocket payments for medications and reasons for changes in treatment were not captured. Further research is warranted to understand the challenges physicians face with decisions surrounding the treatment of epilepsy in Canada.