Abstracts

Rationale: To examine trends of epilepsy surgery as the treatment of medically refractory epilepsy in a universal health system Methods: We performed a population-based retrospective cohort study between fiscal year 1999 and 2010 to assess trends in epilepsy surgery for patients with medically-refractory epilepsy. Linked administrative hospitalization and ambulatory databases from the Canadian Institute for Health Information and the National Ambulatory Care Reporting System were used to identify all epilepsy patients in Ontario, Canada from April 1999 to March 2011. Medically refractory epilepsy patients were distinguished based on the recent ILAE definition. Evidence of epilepsy surgery was examined within 2 years after the patient became medically intractable by Ontario Health Insurance Plan billing codes. Trends for epilepsy surgery, all-cause mortality and epilepsy ambulatory visits among those medically-intractable epilepsy patients were analyzed. Due to the availability of the ambulatory database, separated study cohorts were created. We considered using only the epilepsy hospitalization records for the primary study cohort. Patient demographics, socioeconomic status and mental health conditions were also assessed. Results: In the primary cohort, a total of 7869 epilepsy patients were identified to have medically refractory epilepsy from 1999 to 2010. We observed a minor decreasing number of patients from 1999 to 2002 as a result of decreasing epilepsy hospitalizations in the province (997 patients in 1999, 686 patients in 2002), however the cohort number remained stable from 2002 onwards. Equal numbers of female and male patients were found (50.2% female) with a median age of 48 years old (IQR:36-62). A majority of patients resided in urban areas (86.6%) and were identified as living in a low income neighborhood with high marginality with regard to residential instability, material deprivation, dependency as well as ethnic concentration based on 2001 and 2006 Canadian Census data. Within five years prior of becoming medically intractable, a substantial percentage of patients had a history of Depression and/or Anxiety (30.6% with Depression history; 61.1% with Anxiety history). Only a small proportion of them were in long term care facilities (8.3%). Over the study period, 131 (1.7%) patients received epilepsy surgery treatment within the first two years of becoming medically refractory. The surgery rates per two consecutive fiscal years remained consistently low, ranging from 1.0% to 2.7% Conclusions: The number of patients with medically intractable epilepsy in this sample has been relatively steady between 1999 and 2010. Only a small percentage of these patients received surgical treatment, despite strong evidence in the medical literature favoring surgical treatment in this group of patients.