Epidemiology in Epilepsy

Mortality Risk in Children with Epilepsy: The Dutch Study of Epilepsy in Childhood.

Callenbach PM, Westendorp RG, Geerts AT, Arts WF, Peeters EA, van Donselaar CA, Peters AC, Stroink H, Brouwer OF

Pediatrics 2001;107:1259-1263

Objective. Long-term follow-up studies of patients with epilepsy have revealed an increased mortality risk compared with the general population. Mortality of children who have epilepsy in modern times is as yet unknown. Therefore, the objective of this study was to determine mortality of children who have epilepsy in comparison with the general population.

Methods. Between August 1988 and August 1992, 472 children, aged 1 month to 16 years, who presented in one of the participating hospitals with two or more newly diagnosed unprovoked seizures or at least one status epilepticus were enrolled in the study. All children were followed for five years or until death. The number of deaths observed during follow up was compared with the expected number of deaths in the same age group in the general population in the Netherlands.

Results. Nine children died during follow up, amounting to a mortality rate of 3.8/1000 person-years, which is sevenfold higher than expected (95% confidence interval = 2.4–11.5). No deaths were observed among the 328 children who had epilepsy of nonsymptomatic cause. All deceased children had epilepsy that was caused by a static or progressive neurologic disorder (mortality risk = 22.9; 95% confidence interval = 7.9–37.9). None of them died from sudden unexpected and unexplained death of epilepsy.

Conclusions. In our cohort, we found no indication that children who have nonsymptomatic epilepsy have an increased mortality risk compared with the general population, whereas children who have symptomatic epilepsy have a 20-fold increased mortality risk. These data provide guidance for counseling parents of children who have epilepsy.

COMMENTARY

Mortality is increased over population-based levels in people who have epilepsy. The relative increase in risk appears to be greatest in young people ⁸. The risk and risk factors of mortality in individuals with epilepsy have been the focus of tremendous research efforts recently. It is clear that symptomatic etiology and poor seizure control are consistently two of the strongest predictors of mortality. In addition, the risk appears to be highest relatively early in the course of the disorder and to diminish over time. The recent article by Callenbach et al. from the well-documented Dutch Study of Epilepsy in Childhood is a welcome addition to the current literature.

In their cohort of 472 children, only nine deaths occurred during the first five years of follow up. While this is a small proportion of the cohort, it in fact represents a seven-fold increase in mortality relative to the population. Three of the deaths were in association with progressive disorders and none occurred in children with nonsymptomatic epilepsy. The careful analysis and presentation of mortality by etiology and syndromic grouping further helps to explain the increased risk of mortality in childhood onset epilepsy.

The results of the Dutch study are highly comparable to an entirely independent population-based study from Nova Scotia ⁹ which found a very low overall risk of mortality mostly confined to symptomatic epilepsy. Both studies also demonstrate that the risk of sudden unexplained death in epilepsy (SUDEP) in pediatric epilepsy is very low. There were no cases in the Dutch study and only one in the study from Nova Scotia. Another recent study from the Province of Ontario estimated the incidence rate for SUDEP in children with epilepsy to be 2/10,000 person-years ¹⁰.

Well-done carefully reported epidemiological studies such these as have greatly added to our understanding of this rare but serious outcome of epilepsy.