The epidemiology of epilepsy revisited

Epidemiology is the study of the dynamics of a medical condition in a population. There are many shortcomings in the understanding of the epidemiology of epilepsy mostly caused by methodological problems. These include diagnostic accuracy, case ascertainment, and selection bias. In this article recent progress in this area is discussed and suggestions for future research are made.

It is generally accepted that in developed countries the incidence is around 50/100 000/year. In resource-poor countries, the incidence is likely to be higher. Prevalence of active epilepsy is in the range of 5-10/1000 in most locations, although it might be higher in some isolates. Age-specific incidence rates have changed, with a decrease in younger age groups and an increase in persons above 60 years. The overall prognosis for seizure control is good and over 70% will enter remission. Epilepsy carries an increased risk of premature death particularly in patients with chronic epilepsy. Sudden unexpected death has been increasingly recognized as a major culprit for this increased mortality.

There is geographic variation in the incidence of epileptic syndromes likely to be associated with genetic and environmental factors, although as yet causality has not been fully established. The complete range of aetiologies in the general population is not known. Few predictors of outcome are recognized and it is difficult to prognosticate in any individual case. Knowledge is patchy about the epidemiology of sudden unexpected death in epilepsy. Future epidemiological research needs to address these issues if we are to progress.