Impact of epilepsy on the incidence of injury in Finnish children. A register-based study

Abstract

Objective: To study the association of epilepsy with the incidence of hospital-treated injury among children, with special reference to comorbid intellectual disability (ID). Methods: A population-based cohort of 329,291 Finnish children born during 2001–2006 was followed for the diagnosis of epilepsy and hospital-treated injury until 2012. Information on the cohort was obtained from national registers. Primary outcome variable was first hospital-treated injury. Cases were followed from the diagnosis of epilepsy until first injury, death or 2012. For controls, the follow-up began from birth. Explanatory variables included epilepsy, gender and comorbid intellectual disability (ID). The mean annual incidence of injury per 100,000 person-years and Hazard Ratios (HR) with 95% confidence intervals from Cox regression models was calculated. Attributable risk of injury (AR%) was assessed with Cox proportional hazard regression. Results: A total of 2353 (46% girls n = 1085) cases with epilepsy and 326,938 (49% girls, n=160,196) controls were included. The mean annual incidence of injury was 3204/100,000 person-years among children with epilepsy and 2274/100,000 person-years among controls. The gender adjusted HR was 1.30(1.17–1.45) for epilepsy compared with controls. Epilepsy-related AR was 23%. Of the injured children with epilepsy boys had 3420 and girls 2965 injuries per 100,000 person- years. Children with epilepsy and comorbid ID had higher incidence of injury compared with epilepsy alone (4226 vs. 2951 injuries per 100,000 person-years) with unadjusted HR 1.41(1.10–1.82) for ID. Conclusion: The risk of hospital-treated injury is higher among children with epilepsy than in controls. The risk is further elevated among children with comorbid ID.