Excess mortality in remote symptomatic epilepsy

Published estimates of excess mortality associated with epilepsy vary greatly. How much, if any, of the excess is attributable to the seizures themselves as opposed to an underlying condition causing the epilepsy is not clear from the literature. This article offers evidence that epilepsy per se is associated with excess mortality. The excess varies according to severity and frequency of seizures.

The authors studied mortality rates of developmentally disabled persons in California with and without epilepsy. In order to focus on the effect on mortality risk of epilepsy per se, they included only persons with good motor function (able to walk and climb stairs) and at worst moderate mental retardation (MR). The data were 506,204 person-years and 1523 deaths among 80,682 California subjects of age 5 to 65 years during the 1988-1999 study period. Mortality rates for persons with epilepsy were compared to rates for persons with no history of epilepsy.

Mortality rates were higher for persons with epilepsy than for those without. Excess death rates (EDRs) varied according to type and frequency of seizures. Combined EDRs were 6 (deaths per 1000 person-years) for persons with recent (< 12 months) history of status epilepticus, 5 for recent history of generalized tonic-clonic (GTC) seizures, 3 for recent history of seizures but no recent GTC seizures, and less than 1 for a history of seizures but no recent events.

The data presented here are evidence that epilepsy per se is associated with increased mortality. The EDRs reported here may be better measures of excess mortality due to epilepsy than previously published estimates.