Inpatient admission for febrile seizure and subsequent outcomes do not differ in children with vaccine-associated versus non-vaccine associated febrile seizures

Introduction: Recent data suggest that the risk factors for febrile seizure (FS) can differ depending on whether the FS was vaccine-associated (VA) or not. As such, there also may be differences in the risk of inpatient admission and/or the incidence of FS-related subsequent outcomes following the index FS depending on whether it was VA or non-vaccine associated (NVA). This could have useful clinical implications including caregiver education and planning for follow-up care.

Methods: This cohort study consisted of 3348 children who experienced an index FS between 6 months up to 3 years of age from July 1, 2003 through December 31, 2011. The index FS was determined to be VA-FS or NVA-FS; inpatient admission for FS, recurrent FS, and diagnosis of epilepsy were compared between exposure groups. Hazard ratios and relative risk estimates comparing between VA-FS and NVA-FS were estimated by Cox proportional models and Robust Poisson regression models, adjusted for race, sex, age at first FS, birth weight, gestational age, maternal age, and 1- and 5-min Apgar scores.

Results: The mean age at index FS was 1.5 years; the mean length of follow-up was 2.3 years. Of all index FS, 383 (11.4%) were VA and 2965 were NVA. Among index FS, 264 (7.9%) were admitted as inpatients. Subsequently, 703 (21.0%) children developed at least one recurrent FS, where the number of recurrences ranged from 0 to 9 events. Overall, 144 (4.3%) children were diagnosed with epilepsy during the follow-up period. In adjusted analyses, VA-FS did not differ in the risk for any of the outcomes of interest compared with NVA-FS.

Discussion: The risk of hospitalization for index FS or select subsequent FS outcomes did not differ between VA or NVA-FS. This suggests that the follow-up care of children with VA-FS does not warrant attention beyond that for NVA-FS.