Incidence of childhood epilepsy: A population-based study in rural Japan

Abstract

Introduction

Epilepsy is a common childhood neurological condition and a major public health concern worldwide. A higher incidence of epilepsy is reported in low- and middle-income countries, particularly in rural areas. However, no Japanese reports on the incidence of childhood epilepsy have been published in the past 25 years. We estimated the annual incidence of epilepsy in children aged 1–14 years in Uwajima, a city in a rural, relatively isolated area of Japan.

Methods

Candidates were extracted from Japan’s public insurance database following the International Classification of Diseases code for epilepsy. Epilepsy was defined as two or more unprovoked seizures more than 24 hours apart, as per the International League Against Epilepsy definition. The study sample was divided into three cohorts based on age at diagnosis: 1–4, 5–9, and 10–14 years. The incidence of epilepsy was calculated as the number of children with epilepsy divided by the person-years in each cohort.

Results

The annual incidence rate of epilepsy in children aged 1–14 years was 70.4/100,000 children (95% confidence interval, 44.8–96.0). There was no significant difference in incidence between boys and girls. This rate was similar to those reported in other countries, although the incidence in children aged 1–4 years was slightly higher in our study than in other countries.

Conclusion

The annual incidence of childhood epilepsy in rural areas of Japan is generally comparable with rates of childhood epilepsy reported in other countries.

Introduction

Epilepsy is a serious neurologic disorder that is common in children [1]. A better understanding of its epidemiology will help in developing care systems that go beyond seizure control and address aspects of children’s social, emotional, and developmental wellbeing [2]. New findings may influence how physicians determine an effective course of treatment for pediatric patients, as well as the information they can provide parents and caregivers regarding the risks, recurrence, and long-term prognosis [1]. Although some epidemiological studies have addressed the incidence and prevalence of epilepsy in children, comparison between studies is challenging because of differing methods, definitions of epilepsy, participants’ age range, and inclusion of children with febrile seizures [3]. Guidelines for epidemiologic research were published in 1993 by the International League Against Epilepsy (ILAE), and are usually used for definitions of epilepsy [1], [3].

Most studies on the incidence of childhood epilepsy are restricted to new-onset epilepsy before age 16 years [3]. These studies report rates ranging from 41–187 per 100,000 children, and consistently show that the incidence is highest in the first year of life and declines to adult levels by age 10 years [3]. Nearly all studies found that the incidence did not differ between boys and girls, but was higher in low- and middle-income countries (LMICs), particularly in rural areas [3].

Although the prevalence of childhood epilepsy has been investigated in Japan [4], there have been no reports on the incidence of childhood epilepsy in the past 25 years, meaning there are no available studies that used the ILAE classification system. Our study addressed this gap by estimating the incidence of childhood epilepsy in a rural area of Japan, and comparing this with rates reported in other countries.