Introduction: Several risk factors for sudden unexplained death in epilepsy patients (SUDEP) have been proposed, but subsequent work has yielded conflicting data. The relative importance of various risk factors for SUDEP was never explored. The aim of this study is to review systematically risk factors for SUDEP and also to determine their relevance for SUDEP by calculating relative risk factor ratios.
Methods and materials: Authors performed a literature-search on "SUDEP" in Medline, the Cochrane Library and EMBASE. Studies with unknown number of SUDEP cases or with less than five SUDEP cases and reviews were excluded from further analysis. The value of each paper was assessed, based on the quality of the study and the reliability of the diagnosis of SUDEP. This value ranged from 1 (low quality) to 10 (high quality). Papers with a value below 7 were eliminated for further analysis. For each analysed factor, a risk factor ratio was determined, with a higher ratio for a stronger risk factor.
Results: A number of strong risk factors for SUDEP: young age, early onset of seizures, the presence of generalized tonic clonic seizures, male sex and being in bed. Weak risk factors for SUDEP: prone position, one or more subtherapeutic bloodlevels, being in the bedroom, a strucural brain lesion and sleeping.
Conclusions: In this study, authors have designed a quality scale to select papers. The relative importance of risk factors for SUDEP is demonstrated.