Abstracts

Rationale: Knowledge is lacking on the epidemiology of specific epilepsy syndromes outside of a hospital setting. This may provide useful information not only on the population burden of disease, but also the common etiological factors acting at the population-level. Methods: Patients prescribed antiepileptic drugs in Tasmania between 01.07.01 to 30.06.02 were invited to participate on the Tasmanian Epilepsy Register (TER). A validated diagnostic questionnaire was used to classify patient’s seizures and the presence of IGE. Interviews were conducted using computer-assisted-telephone-interviewing, which were interpreted by an epileptologist using standardised diagnostic guidelines. Results: 959/1083 (88.6%) eligible TER participants completed the diagnostic telephone interviewing: uncertain epilepsy 3.6%, uncertain partial or generalised epilepsy 8.3%, partial epilepsy 66.4% and generalised epilepsy 21.7%. IGE was diagnosed in 20.3%, with tonic-clonic seizures (17.03%) the most common generalised seizure type and the absence epilepsies combined (11.01%) the most common IGE syndromes. The estimated prevalence of IGE was 0.89 per 1000; highest between the ages of 20-39 years and in females, but similar between Tasmanian regions and socio-economic groups. Generalised seizures, but not IGE, showed unexplained regional differences. IGE beyond adolescence related to refractory childhood or adolescent disease rather than older-onset cases, and was characterised by the presence of myoclonic and tonic-clonic seizures. Conclusions: IGE is a common group of epilepsies and has important aetiological and prognostic determinants at the seizure level of classification.