The incidence of sudden unexplained death (SUD) among patients less than 50 years old with refractory epilepsy was determined at Boston University Medical Center, Lexington, MA, and Department of Epidemiology, Glaxo Wellcome, Research Triangle Park, NC. Subjects receiving two or more anticonvulsants concurrently were identified from the General Practice Research Database in the UK and their clinical records were reviewed. Of 4150 patients with refractory epilepsy, 612 (15%) were under 20 years of age. For all subjects, including both idiopathic and acquired epilepsies, the incidence rate of highly probable SUD was 1.5/1000 person-years; for highly probable and possible categories combined, the incidence rate was 2.2/1000 person-years. The respective rates for idiopathic and acquired epilepsy separately were 2.4 and 1.0/1000 person-years. Of a total of 15 subjects with SUD and epilepsy, 8 male and 7 female, 2 (13%) were younger than 20 years. 
COMMENT. Idiopathic refractory epilepsy was associated with an estimated risk of sudden unexplained death of 2.4/1000 person-years, whereas the risk with acquired refractory epilepsy was 1.0/1000. A previous study has estimated a higher risk of SUD in patients with acquired epilepsy. The authors concede that relevant information on the cause of epilepsy may have been omitted in some records, leading to an overascertainment of idiopathic cases.
Male sex, the need for multiple AEDs, and use of psychotropic drugs were risk factors for SUD in a Canadian study which showed an overall rate of 1.35/1000 person-years. (see Ped Neur Briefs Jan 1995;9:1 for review and commentary). Cardiac causes for idiopathic seizures and a normal EEG, a possible explanation for some cases of SUD, especially in adolescent males, should always be considered when AEDs are ineffective.