RISK-FACTORS FOR SEIZURE RECURRENCE IN CHILDREN WITH FEBRILE SEIZURES- A POOLED ANALYSIS OF INDIVIDUAL PATIENT DATA FROM 5 STUDIES

To reassess the relations between postulated risk factors and seizure recurrence after a first febrile seizure (FS), the individual data fro m five follow-up studies that used similar definitions of FSs and risk factors were pooled and reanalyzed. The risk of frequent recurrent se izures and of the occurrence of complex seizures in previously healthy , untreated children was studied. Seizure recurrence hazard was descri bed as a function of the child's attained age. The influence of variou s risk factors on the recurrence hazard was assessed, with control for other factors. Of a total of 2496 children with 1410 episodes of recu rrent seizures, 32% had one, 15% had two, and 7% had three or more rec urrent seizures after a first FS; 7% had a complex seizure. The hazard of recurrent seizures was highest between the ages of 12 and 24 month s. After a first and a second recurrence, the risk of further FSs was two and two and one-half times higher, respectively. A history of febr ile or unprovoked seizures in a first-degree family member and a relat ively low temperature at the time of the first seizure were also assoc iated with an increased risk of subsequent recurrences. Young age at o nset (< 12 months), a family history of unprovoked seizures, and a par tial initial FS were all associated with an increased risk of complex seizures. A higher recurrence rate in clinic-based studies compared wi th population-based studies could not be explained by a difference in the presence of the risk factors studied. Thus other factors must infl uence seizure recurrence after an initial FS.