Febrile seizures: Are they truly benign? Longitudinal analysis of risk factors and future risk of afebrile epileptic seizure based on the national sample cohort in South Korea, 2002–2013

Abstract

We performed a large, population-based study to analyze the risk factors of the febrile seizures and the subsequent afebrile epileptic seizures. Methods: Relevant data from children born between 2002-2007 were retrieved from the Korean National Health Insurance Service-National Sample Cohort 2002-2013. Children who did not survive the first five years were excluded from the analysis. The risk factors for febrile seizures were assessed separately in per-person and perfebrile case analyses, and factors contributing to an increased risk of subsequent afebrile epileptic seizures were identified. Results: A total of 54,233 children were included and the five-year prevalence rate of febrile seizure was 11.19%. In the per-person analysis, male sex, preterm birth and brain injury at birth increased the risk of febrile seizure with odds ratios of 1.17, 1.40 and 1.97 (all p < 0.001), respectively. A high household income level was associated with reduced odds of febrile seizure. In the per-febrile illness analysis, male sex, brain injury at birth, presumed bacterial infection, gastrointestinal or genitourinary infection and unspecified sepsis were independent risk factors of a febrile seizure during febrile illness. The cumulative number of febrile seizure episodes, especially more than the third episodes, was associated with a new diagnosis of an afebrile epileptic seizure within one year. Conclusion: Sex, preterm birth, brain injury at birth, presumed bacterial infection, genitourinary and gastrointestinal infections and unspecified sepsis were identified as likely risk factors for febrile seizures. A greater number of febrile seizure episodes was associated with a higher probability of subsequent afebrile epileptic seizures.

Seizure prevalence in children aged up to 3 years: a longitudinal population-based cohort study in Japan

“… 24 The rate in South Korea is also high, at 11.2% in children aged up to 5 years. 11 In contrast, the prevalence rate of febrile seizure is 2.3% in the UK, 10 3.4% in the USA, 6 4.3% in Turkey, 15 4.9% in Denmark, 22 6.9% in Finland 25 and 10.1% in India. 27 These geographical differences are attributed mainly to the racial and genetic factors.…”

“…We were also unable to identify the lifetime prevalence of febrile seizures. Most previous studies included children aged up to 5 years 10 11 22 24 25 27 ; however, our study only included children aged up to 3 years, similar to a few Japanese studies. 7 21 Therefore, the lifetime prevalence of febrile seizures in Japan might be higher than that in our study.…”

Simple Febrile Seizures: A Benign Phenomena?

“…The incidence seems to be higher in some eastern European populations (8-10% incidence). 5 Up to 90% of children with SFS have experienced a convulsive event before the age of 3 years, with the peak incidence occurring between ages 18 and 24 months. In addition, only 6% of children experience a seizure before 6 months and 4% after 3 years.…”

“…The most important predictive risk factors for the development of epilepsy are developmental delay, abnormal neurological exam prior to the febrile seizure, history of complex febrile seizures or febrile status epilepticus, and a first degree relative with epilepsy. 5,9,34 The exact mechanism for development of epilepsy is complex and not fully elucidated. These risk factors may suggest a preexisting predisposition to develop epilepsy.…”

“…These findings suggest that not all SFS are a completely benign process. 5 A small proportion of patients with SFS present with status epilepticus. Febrile status has been associated with younger age, lower body temperature, longer duration of the fever, female sex, structural temporal lobe abnormalities (identified on MRI), and first degree relative with febrile seizures.…”