Predictors of multiple seizures in a cohort of children prospectively followed from the time of their first unprovoked seizure

The objective of this study was to assess the risk of multiple recurrences after an initial seizure recurrence in childhood. In a prospective study, 4 07 children were followed for a mean of 9.6 years from the time of their fi rst unprovoked seizure. Data regarding each seizure recurrence were obtaine d and analyzed using statistical methods for survival analysis. The cumulat ive risk of a second seizure was 29%, 37%, 43%, and 46% at 1, 2, 5, and 10 years, respectively. Of the 182 children who experienced a second seizure, 131 (72%) experienced a third seizure, 105 (58%) have bad 4 or more seizure s, and 52 (29%) have experienced 10 or more seizures, The cumulative risk o f a third seizure was 57%, 63%, and 71% at 1, 2, and 5 years, respectively, after the second seizure. After a third seizure, the cumulative risk of an other seizure was 69%, 72%, and 81% at 1, 2, and 5 years, respectively, Aft er a second seizure, factors associated with an increased risk of additiona l recurrences included a remote symptomatic etiology (rate ratio = 1.7) and the occurrence of a second seizure within 6 months of the first seizure (r ate ratio = 1.7). After a second seizure, the risk of subsequent seizures w as greater than 50% even in the lowest risk group. With the exception of et iology, factors associated with an increased risk of multiple recurrences a fter the initial seizure were different than those associated with multiple recurrences after a second seizure. Factors associated with multiple recur rent seizures may be different than those associated with an initial recurr ence. As most patients who experience a second seizure experience further s eizures, these data suggest that two seizures are a sufficient epidemiologi cal criterion for the definition of epilepsy.