Risk factors of epilepsy in children with complex febrile seizures; A Retrospective cohort study.

BACKGROUND Febrile seizures are the most common seizures in children. Children with complex febrile seizures have a higher risk of subsequent epilepsy compared with children with simple febrile seizures. Multiple risks factors of epilepsy including focal status epilepticus, family history of epilepsy, neurodevelopmental abnormalities and abnormal EEG findings have been found with inconsistent results. The aim of this study is to identify risk factors for developing epilepsy in children with complex febrile seizures. METHODS The study comprised 248 children aged 3 to 72-months diagnosed with complex febrile seizures at Chiang Mai University Hospital. Multiple risk factors including demographic data, seizure characteristic, EEG and neuroimaging findings were identified and assessed if they were risk factors of subsequent epilepsy. RESULT Fifty-five patients (22.1%) had subsequent epilepsy. Using Cox regression-survival analysis, factors associated with epilepsy were prolonged seizures >15 mins (p=0.006; HR 2.475; 95%CI 1.294 - 4.735), developmental delay (p =0.019; HR 4.476; 95%CI 2.280-15.646), epileptiform discharges on electroencephalogram (EEG) (p = 0.023; HR 1.391; 95%CI 1.174 - 1.876), and abnormal neuroimaging (CT or MRI) (p = 0.028; HR 1.355; 95%CI 1.034-1.776). Age at onset, peak febrile temperature, duration between the onset of fever and the occurrence of seizure, recurrent seizures within 24 hours, focal seizures, abnormal neurological exam and family history of febrile seizure or epilepsy were not associated with increased risk of subsequent epilepsy in this study. CONCLUSION Risk factors associated with increased risk of epilepsy in children with complex febrile seizures are prolonged seizures or febrile status epilepticus, developmental delay, EEG epileptiform discharges and abnormal neuroimaging. Their presence would merit close clinical monitoring.