ArticlesRisk factors for sudden unexpected death in epilepsy: a case control study
Introduction
People with epilepsy have an increased risk of sudden unexpected death. The incidence of sudden unexpected death in epilepsy (SUDEP) depends on the population under study; it ranges from 1 per 100 patient-years in therapy-resistant epilepsy-surgery candidates to 1 per 1000 in studies based on prevalent cases and to 3·5 per 10 000 in investigations based on incident cases,1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 as summarised by O'Donaghue and Sander.14
Although several suggestions have been made, the physiological mechanisms underlying SUDEP remain unclear.15, 16, 17, 18 Without established explanations for SUDEP, the analysis of possible risk factors becomes important. Previous studies have suggested that low age, being male, remote symptomatic epilepsy, intractability (poor response to treatment), alcoholism, treatment non-compliance, and recent head trauma are associated with increased risk. However, the value of these observations is limited because in general the studies lack relevant control groups, comprise few cases, and are often based on selected populations of patients. Nashef and Brown19 have already emphasised the need for case-control studies.
We have done a population-based, nested, case-control study of SUDEP within a large cohort of adult epilepsy patients in Stockholm, Sweden. Our aim was to investigate the association between some clinical characteristics and SUDEP, focusing mainly on risk factors suggested by previous investigators.
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Study population
We have described our study population in more detail previously.20 In brief, all participants were aged between 15 and 70 years, were living in Stockholm, and, at least once between 1980 and 1989, were admitted to hospital and discharged with a diagnosis of epilepsy, identifiable on the Stockholm County Inpatient Register. We thus identified a study population of 6880 people, and estimated that more than 60% of the adult epilepsy population in Stockholm is included in this cohort.20 The study
Results
We found a significantly low RR for SUDEP associated with cerebrovascular disease, and a low RR for SUDEP associated with heart disease (though it did not reach significance). We also found an increased risk associated with injuries (other than injuries to the central nervous system) and with dementia (table 2).
Seizure frequency was the factor most strongly associated with an increased risk of SUDEP (table 3). Fewer cases (1·8%) than controls (31·6%) were seizure-free during the last year of
Discussion
Previous information on risk factors for SUDEP comes from selected cohorts such as case series from epilepsy referral centres,1, 2, 5 from residences for patients with intractable epilepsy,3, 4 from coroner's offices,12, 24 and, in a few cases, from larger cohort studies.6, 7, 11 The paucity of studies allowing comparison with a relevant control group within the study has been underlined elsewhere.19, 25 The few available case-control studies have compared small numbers of SUDEP cases from
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2022, JACC: Clinical ElectrophysiologyCitation Excerpt :On the other hand, all of the remaining components of the VFRisk are novel as incorporated in a risk score. All of these clinical and ECG variables have been reported as having individual associations with increased risk of SCD.14-16,19,27,28 The inclusion of echocardiographic LVH in a clinical risk score for SCD is also new.21