Risk of recurrence and outcome after the first febrile seizure.

After their first febrile seizure, 180 children were prospectively monitored to provide data for a quantitative and qualitative analysis of the factors affecting the risk of recurrence of febrile seizures and to evaluate the influence of recurrences on the outcome. Of these children, 153 had subsequent febrile episodes and were included in the risk-factor analysis. The outcome was evaluated after a 2-year follow-up in 156 children. Each febrile episode increased the risk of recurrence by 18%. Each degree of increase in temperature (Celsius) during subsequent infections almost doubled the risk of recurrence. Age, sex, the type of initial seizure, the temperature during the initial seizure, or a family history of febrile seizures or epilepsy did not influence the recurrence rate significantly. The results indicate that procedures that minimize the probability of febrile infections would decrease the risk of recurrences of febrile seizures.