Febrile Seizures and Subsequent Autism Spectrum Disorder: A Nationwide Population-Based Cohort Study

<b>Objectives:</b> To access the effects of febrile seizures from coexisting neurodevelopmental conditions that are commonly associated with autism spectrum disorder. We examined whether febrile seizures are independently associated with ASD after considering neurodevelopmental comorbidities and seizure-related clinical characteristics. <b>Methods:</b> We conducted a nationwide population-based matched cohort study using Taiwan's National Health Insurance Research Database. The study included 948 children with FS and 3804 age- and sex-matched controls without FS. Participants were followed longitudinally for incident ASD. Associations were evaluated using Cox proportional hazards models with additional analyses restricted to the FS cohort. Neurodevelopmental comorbidities assessed included attention-deficit/hyperactivity disorder (ADHD), epilepsy, and Tourette syndrome/tic disorder. <b>Results:</b> Among 4752 children followed for more than 10 years, 43 (0.9%) developed ASD. FS were not independently associated with ASD in adjusted Cox regression models. In contrast, ADHD, epilepsy, and Tourette syndrome/tic disorder were strongly and consistently associated with ASD across analytic models. <b>Conclusions:</b> Febrile seizures were not independently associated with autism spectrum disorder. Instead, ASD risk was largely explained by coexisting neurodevelopmental comorbidities, consistent with a shared neurodevelopmental susceptibility framework. These findings suggest that developmental surveillance should prioritize children with neurodevelopmental disorders rather than those with febrile seizures alone.