Febrile convulsions after 5 years of age: long-term follow-up.

In order to examine the natural history of febrile convulsions occurring after 5 years of age, we studied 44 children in whom febrile convulsions persisted after 5 years of age (group 1) and compared their development of unprovoked seizures with a group of 195 children in whom febrile convulsions occurred before 5 years of age (group 2). All subjects of group 1 were re-evaluated at the mean age of 13.4+/-1.7 years. The children in group 2 were followed up until they reached the same mean age as children in group 1 (13.1+/-2.3 years). In group 1, we found a higher percentage of unprovoked seizures than in children with febrile convulsions with onset before 5 years of age (18.1% vs 7.4%, P < .05). Our data suggest that children with febrile convulsions after 5 years of age probably must be considered as a group of patients at risk of developing unprovoked seizures.