Abstracts

Rationale: Epilepsy is one of the most common neurological conditions worldwide. The purpose of this study was to estimate the international incidence of epilepsy and explore sources of heterogeneity between studies. This study was part of a larger initiative funded by the Public Health Agency of Canada, the National Population Study of Neurological Conditions, to facilitate a better understanding of the burden of 15 neurological conditions in Canada and worldwide. Methods: MEDLINE and EMBASE databases (1985 to Dec 13, 2010) were searched for this systematic review using pre-specified MeSH terms and keywords related to seizures, epilepsy, convulsions, incidence, prevalence and epidemiology. Population-based studies reporting the incidence and/or prevalence of epilepsy were included. Studies focusing solely on febrile convulsions or seizures (not epilepsy) were excluded. Two reviewers independently reviewed all abstracts, full text articles and abstracted data. A third reviewer was consulted to resolve any disagreement. Reported prevalence and/or incidence were abstracted for each study. A random effects model was used to pool the average annual incidence (AAI) [95% confidence interval] per 100,000 people as well and the incidence rate per 100,000 person-years of epilepsy (after testing for heterogeneity). Results: Embase and Medline identified 8061 and 5191 abstracts respectively, with 442 abstracts selected for full text review with 33 articles meeting all eligibility criteria. Incidence studies were identified in Europe (n=20), North America (n=4), Africa (n=4), South America (n=3) and Asia (n=2), with most studies originating from Iceland (n=3), the UK (n=3), and the USA (n=3). No Canadian studies addressing the incidence of epilepsy were identified. The most important source of heterogeneity was whether the examined region was developed or developing, with higher average annual incidence and incidence rate in developing countries. The highest AAI was reported in the Kenya pediatric study at 187.36 (114.12-307.61) per 100,000 children per year, with the lowest AAI reported in the Netherlands at 29.50 (22.17-39.236) per 100,000 people per year. The highest incidence rate was reported in Uganda at 215 (157.76-293.01) per 100,000 person-years while the lowest incidence rate was reported in the USA at 15.15 (12.20-18.81) per 100,000 person-years. Conclusions: Epilepsy is common, particularly in developing countries, although significant gaps still exist regarding the incidence of epilepsy worldwide, even in developed countries such as Canada. The higher incidence found in developing countries is consistent with prior studies, and is believed to be multifactorial, and likely due in part to possible genetic factors, but more significantly to the higher incidence of infections and head trauma in resource poor countries. Stratified AAI and incidence rate will be discussed, along with various sources of heterogeneity. There is a need for more uniform definitions of epilepsy and comparable methods of ascertainment for future epidemiological studies.