Background: Febrile seizures affect 2 to 4% of children, and 2 to 10%
develop subsequent unprovoked seizures, Secondary analyses of two larg
e cohorts identified neurodevelopmental abnormalities, complex febrile
seizures, and a family history of epilepsy as predictors of unprovoke
d seizures. We present an analysis of children prospectively followed
from their first febrile seizure to reassess these three factors, exam
ine factors of equivocal importance, and assess the importance of some
new factors that we identified as predictors of recurrent febrile sei
zures. Methods: Children (N = 428) were prospectively identified for a
first febrile seizure through pediatric emergency departments of four
hospitals. Information was collected from medical records and intervi
ews with parents. Children were followed for 2 years or-more. Results:
Unprovoked seizures occurred in 26 (6%). Neurodevelopmental abnormali
ties, complex febrile seizures, and a family history of epilepsy were
associated with an increased risk of unprovoked seizures. Recurrent fe
brile seizures and brief duration of fever before the initial febrile
seizure were also risk factors. A family history of febrile seizures,
temperature and age at the initial febrile seizure, sex, and race were
not associated with unprovoked seizures, Conclusions: We confirmed th
e increased risk associated with traditionally accepted predictors of
epilepsy following febrile seizures. Also, the risk clearly increased
with recurrent febrile seizures. In general, predictors of subsequent
unprovoked seizures differ from predictors of recurrent febrile seizur
es. One notable exception, brief duration of fever before the initial
febrile seizure, predicts both types of outcome and may be a marker fo
r an increased susceptibility to seizures.