Incidence of sudden unexpected death in epilepsy in community-based cohort in China
Introduction
Sudden unexpected death in epilepsy (SUDEP) is associated with the premature mortality seen among people with epilepsy. In western countries, the incidence of SUDEP varies with the sample population, increasing from 0.35 to 2.3 in community samples to 1.1 to 5.9 in epilepsy clinics and between 6.3 and 9.3 in participants of epilepsy surgery programs [1]. One long-term study reported that in a cohort of people with epilepsy followed for over 30 years, SUDEP accounted for a third of all death [2].
There have been some Chinese case reports of SUDEP with autopsy but overall studies of SUDEP are still limited in China where there are over 9 million people with epilepsy [3].Only two prospective mortality studies have been reported from China [4], [5]; and they did not estimate SUDEP incidence making comparisons with reports from other countries difficult. The large variation in the proportional mortality ratios for SUDEP (14.7% [4] and 1% [5]) between these two studies suggests some methodological shortcomings in the diagnosis of SUDEP. Autopsies are rarely acceptable in Asia particularly in China and this compounds the issue.
We attempted to estimate the incidence of SUDEP in a Chinese population using specifically designed instruments to overcome some of the shortages and to report detailed information about cases identified.
Section snippets
Study cohort with epilepsy
Between January 2010 and December 2011, people with epilepsy were recruited from rural areas in the Chinese provinces of Henan, Shanxi, and Ningxia, as a part of the “Validation of Clinical Assessment Tools for Population Genetic Studies of Epilepsy (1R21NS069223-01, NIH/NINSD)”. All people with epilepsy aged 2–80 years were eligible for inclusion; they were, however, excluded for the following reasons: 1) if they had nonepileptic attack disorder, 2) if their seizures were related to alcohol or
Characteristics of subjects at the baseline and follow-up
A total of 1562 people were enrolled (baseline clinical and demographic characteristics provided in Table 1. Sixty percent were on antiepileptic drug (AED) monotherapy, and only 20% were in one-year remission when enrolled. A study flowchart is provided in Fig. 1. We were unable to determine survival status of 105 people in both two follow-ups thus the lost-to-follow up rate was 6.7%. No significant differences were found for baseline characteristics between those who were followed and those
Discussion
In this prospective community-based Chinese study, we identified cases of SUDEP and estimated a relatively high incidence for SUDEP. Studies from high-income countries suggest that SUDEP is responsible for up to a third [2], [10], [11], [12] of deaths and its leading cause of epilepsy-related death [2]. There are little data concerning SUDEP in China as only two studies have reported the proportional mortality ratios of SUDEP in epidemiological studies. A study from West China reported 15
Conclusion
There are over nine million people with epilepsy in China. Our results suggest that SUDEP may kill over 20,000 people yearly. Further prospective Chinese studies with larger sample size and longer follow-up periods are urgently needed to examine risk and protective factors in order to seek proper interventions to reduce the burden of SUDEP.
The following are the supplementary data related to this article.
Author disclosures
YG, DD, BY, QZ, TW, WW, BL, JW, JL, PK, and ZH report no disclosures; JWS has received research funding from Eisai, GSK and UCB, personal fees from Eisai, UCB Lundbeck, and Teva, outside the submitted work.
Ethical publication statement
We confirm that we have read the journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.
Acknowledgments
We thank all the village physicians for their hard field work of follow-up, and all participants for their cooperation. JWS is based at UCLH/UCL Comprehensive Biomedical Research Centre, which receives a proportion of funding from the UK Department of Health's National Institute for Health Research Biomedical Research Centers funding scheme. He receives support from the Dr. Marvin Weil Epilepsy Research Fund and UK Epilepsy Society. This study was funded by National Natural Science Foundation
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