Background and Objectives The effect of new-onset seizures in young stroke survivors on the subsequent development of dementia is poorly understood. This study aimed to assess the association between new onset of seizure and dementia in a population-based study of patients with stroke.
Methods The IBM Watson Health MarketScan Commercial Claims and Encounters database for the years 2005–2014 served as the data source for this study. Using the International Classification of Diseases, Ninth Revision (ICD-9), we identified patients aged 18–60 years with ischemic strokes (ISs; 433.x1, 434.x1, and 436) and hemorrhagic strokes (HSs; 430, 431, 432.0, 432.1, and 432.9) between January 1, 2006, and December 31, 2009, which constituted our baseline study cohort. At baseline, all included participants were free of claims for dementia, brain tumors, toxin exposure, traumatic brain injury, and neuroinfectious diseases, identified using ICD-9 codes. They had at least 1-year continuous enrollment before the index stroke diagnosis and 5 years after, with no seizure claims within 1 year after the index date. The exposure of interest was seizures: a time-dependent variable. The study outcome of interest was dementia (ICD-9: 290.0, 290.10–13, 290.20–21, 290.3, 290.40–43, 291.2, 292.82, 294.10–11, 294.20–21, 294.8, 331.0, 331.11, 331.19, and 331.82), which occurred during the follow-up period from January 1, 2010, to December 31, 2014. A Cox proportional hazards regression model was applied to calculate the hazard ratio (HR) and 95% CI for the independent association of seizures with the occurrence of dementia.
Results At the end of the baseline period, we identified 23,680 patients with stroke (IS: 20,642 and HS: 3,038). The cumulative incidence of seizure was 6.7%, 6.4%, and 8.3% for all strokes, IS, and HS, respectively. The cumulative incidence of dementia was 1.3%, 1.4%, and 0.9% for all strokes, IS, and HS, respectively. After multivariable adjustment, young patients with stroke who developed seizures had a greater risk of dementia compared with those without seizures (all strokes adjusted HR: 2.53, 95% CI 1.84–3.48; IS: 2.52, 1.79–3.53; HS: 2.80, 1.05–7.43).