Abstracts

The mortality of individuals with epilepsy is 2-3 times that of the general population. This is attributable to underlying diseases and to epilepsy itself. Sudden unexpected death in epilepsy (SUDEP), an important epilepsy-related cause of death, has recently aroused interest. The reported incidence varies substantially among studies.
To analyze the importance of the source of study population, as compared to other variables, on the estimates of incidence of SUDEP, using a rigorous systematic review process. An expert in library resources and electronic databases searched the Medline, Index Medicus, and Cochrane databases. We also searched bibliographies of pertinent review and original articles, book chapters and expert consultation. Two reviewers independently applied the following inclusion criteria: retrospective and prospective cohort studies without age limitation, containing extractable information about incidence. We excluded duplicate publications. We assessed the methodological quality of individual studies using established principles for epidemiological research. Two investigators independently extracted data, and resolved disagreements through discussion. Of 404 initial articles, 74 potentially eligible studies were reviewed in full text, and 31 fulfilled eligibility criteria. There was substantial between-study variability in the methodology, source of study populations, and definition of SUDEP. The annual incidence of SUDEP ranged from 0.09:1000 to 10:1000. Source of study population strongly correlated with incidence, which was higher in studies from epilepsy clinics and referral centers (1.2:1000 to 10:1000) than in those from the general population (0.09:1000 to 1.3:1000). The incidence ranged from 1:1000 to 10:1000in patients with mental retardation, and from 0:1000 to 0.1:1000 in children. Risk factors for SUDEP were inconsistent among studies. Although there is substantial variability in the incidence of SUDEP among different patient populations, common themes emerge. SUDEP was rare in children On the other hand, SUDEP was more frequent in epilepsy clinics or surgery programs than in coroners reports and general population, suggesting that patients with more intractable and more severe epilepsy may have a higher risk of SUDEP. The role of methodological differences and study populations is explored.