Pediatric Acute Encephalopathy in Japan: A Nationwide Database Study

Pediatric acute encephalopathy is a life-threatening neurological condition that can lead to long-term sequelae. Although previous studies have examined the clinical features of pediatric acute encephalopathy, large-scale epidemiologic data remain limited.

We conducted a retrospective cohort study using the National Database of Health Insurance Claims, which covers nearly the entire Japanese population. Pediatric patients (<15 years) were identified as having acute encephalopathy based on diagnostic codes, brain imaging, and the hospitalization period. We analyzed the incidence of acute encephalopathy, mortality rate, time from diagnosis to death, age distribution, epilepsy management, and initiation of home medical care during 3 years after diagnosis.

Between 2014 and 2018, 6620 pediatric acute encephalopathy cases were identified, with an annual incidence rate of 7.4-9.5 per 100,000 children aged <15 years. The median (interquartile range) age at diagnosis was 2 (1-6) years, and boys accounted for 53.5%. The 3-year mortality rate ranged from 2.3% to 3.4%. The median time from diagnosis to death was 13 days (2-102). Epilepsy management was observed in 19.2% of patients. Home medical care was initiated in 3.3% of patients, primarily for enteral nutrition and respiratory support. The influenza virus was the most frequently associated pathogen.

This study is the most extensive nationwide epidemiologic analysis of pediatric acute encephalopathy in Japan. Our findings highlight the acute and long-term burdens of this disease, improving the understanding of its epidemiology.