Data analysis reveals significant risk factors for sudden unexpected death in epilepsy

Sudden unexpected death in epilepsy (SUDEP) is the most common condition-related cause of death in chronic epilepsy. Case-control studies using living people with epilepsy as controls have aimed at identifying factors that distinguish the epilepsy patient at risk of SUDEP, but there are disagreements between studies and a lack of precision in the risk estimates attributed, in part, to the small number of cases in each study. To counterbalance these study limitations, the Epidemiology Task Force of the International League Against Epilepsy (ILAE) pooled data from four published studies of SUDEP from the U.S., Sweden, Scotland and England.

SUDEP in the study was defined as 1) having a history of epilepsy (one or more seizures during a five-year period), 2) death occurring suddenly, 3) death unexpected with no life-threatening illness, 4) death remaining unexplained after all investigative efforts, including autopsy. (Platform C.03)

Analysis of the pooled data revealed statistically significant risk factors for SUDEP, including increased frequency of generalized tonic-clonic seizures (GTCS), taking more than one anticonvulsant medication (AED), long duration of epilepsy, young age at onset, gender, symptomatic cause, and lamotrigine therapy. The results persisted for both people younger than age 16 and for adults over the age of 16.

According to epidemiologist Dale C. Hesdorffer, Ph.D., of Columbia University, "The emerging profile from our pooled analysis indicates that people with early onset refractory symptomatic epilepsy who have frequent GTCS and take more than one AED are at highest risk. The results suggest that reducing the number of these generalized seizures is a priority of more importance than reducing the number of AEDs."

The researchers also say the role of AEDs and other forms of treatment should be analyzed further in future studies. A further challenge for future research is to focus on patients with refractory epilepsy to clarify what features may distinguish the patients in this high risk population that die in SUDEP from those who survive.