Temperature, age, and recurrence of febrile seizure

Objective: Prediction of a recurrent febrile seizure during subsequent epis odes of fever. Design: Study of the data of the temperatures, seizure recurrences, and bas eline patient characteristics that were collected at a randomized placebo c ontrolled trial of ibuprofen syrup to prevent febrile seizure recurrences. Setting: Two pediatric hospitals in the Netherlands. Patients: A total of 230 children with an increased risk of febrile seizure recurrence. Main Outcome Measure: Seizure recurrence during a subsequent lever episode. Results: A total of 509 episodes of fever were registered with 67 recurrenc es; 35 (52%) recurrences within the first 2 hours after fever of onset had a lower median temperature (39.3 degrees C) than 32 (48%) after more than 2 hours of fever (40.0 degrees C, P<.001). Poisson regression analysis resul ted in 3 univariably significant (P<.05) predictors of a recurrence of seiz ure during a subsequent episode of fever. In a multivariable model, they we re corrected for their correlation: interval between the last previous seiz ure and fever of onset less than 6 months (relative risk = 1.3 [95% confide nce interval: 0.8-2.4]), age at fever of onset (relative risk = 0.7 [95% co nfidence interval: 0.5-1.0] per year increase) and temperature at fever of onset (relative risk = 1.7 [95% confidence interval: 1.1-2.8] per degree Ce lsius increase). Conclusions: Half of the recurrent seizures occur in the first 2 hours afte r fever of onset of a subsequent fever episode. If seizure recurs at a late r time, the temperature at seizure is higher compared with recurrences occu rring in the first 2 hours of fever. Young age at fever of onset, high temp erature at fever of onset, and high temperature during the episode of fever are associated with an increased risk of a recurrent febrile seizure at th e moment that a child with a history of febrile seizures has fever again.