Stroke after adult-onset epilepsy: a population-based retrospective cohort study

Earlier studies indicate a higher risk of subsequent stroke in PWE aged ≥60. However, little is known of the incidence of subsequent stroke in people with epilepsy (PWE) aged 35 through 60. We determined the risk factors that increase the incidence of stroke following adult-onset epilepsy in a large statewide population over a 10-year period.

South Carolina hospital discharge and emergency department (ED) data from 2000 to 2011 were used. The study was limited to persons aged ≥35years without prior stroke. Cases included patients diagnosed with epilepsy who were hospitalized or visited the ED. Controls were people with an isolated fracture of the lower extremity without any history of epilepsy or seizure disorders, presumed to approximate the health status of the general population. Epilepsy, fracture, stroke, and comorbid conditions were ascertained by diagnostic codes from health-care encounters. Only persons having stroke occurring ≥6months after the onset of epilepsy or after the first clinical encounter for controls were included. Cox proportional hazards modeling was performed to determine the risk of stroke.

There were 21,035 cases with epilepsy and 16,638 controls who met the inclusion criteria. Stroke incidence was 2.5 times higher following adult-onset epilepsy (6.3%) compared with controls (2.5%). After adjusting for comorbidities and other factors, cases with epilepsy showed a 60% higher risk of stroke (HR=1.6; 95% CI: 1.42-1.80) compared with controls. Nearly half of the strokes in cases with epilepsy occurred in those with first diagnosis between ages 35 and 55. Somatic comorbidities associated with increased risk of stroke were more prevalent in cases with epilepsy than controls yet similar in both groups with stroke. Risk of stroke increased with increasing age in both groups. However, the risk of stroke in cases with epilepsy increased faster and was similar to that in controls who were ≥10years older.

Adult-onset epilepsy at age 35 and older warrants consideration for occult cerebrovascular disease as an etiology of the epilepsy, which may also increase the risk of subsequent stroke. Somatic comorbidities frequently associated with epilepsy include comorbid conditions that share the same underlying pathology with stroke (i.e., hypertension, hyperlipidemia, myocardial infarction, diabetes, and arteriosclerosis). This increased risk of stroke in patients with adult-onset epilepsy should dictate the evaluation and management of stroke risk factors to prevent stroke.