A follow-up of an incident case-referent study of febrile convulsions seven years after the onset

A cohort of 92 children with an initial febrile convulsion (FC), prospectively identified in a community-based study 1985-1987, was compared with a cohort of 185 age- and sex-matched referents from the same study area. The median time of follow-up was 6.7 years (range: 5.7-7.7) and the median age at follow-up was 8.3 years (range 6.5-14). The cases had their first FC at a median age of 18 months (range 5-67 months), their second FC at 24 months (11-108 months) and their third FC at 26 months (13-92 months). FC recurred in 42% of the FC cohort, and 3.8% of the children in the referent cohort experienced FC. Single or recurrent afebrile seizures occurred in 4.3% and epilepsy in 3.3% of the FC cohort, while no afebrile seizures occurred in the referent cohort. The risk of having a sibling with FC was three times (95% confidence interval 1.3-6.2) higher in the FC cohort, while there was no difference between the cohorts in the risk of siblings developing afebrile seizures. There was no difference between the cohorts in the utilization of health services during the follow-up period. Two children in the FC cohort went to a school for the mentally retarded. There was no aetiological relationship between the FC and the mental retardation in these cases. All other children attended normal schools and none needed remedial instruction.