Risk of stroke after new-onset seizures.

Purpose: Observational cohort studies have reported a potentially increased risk of stroke in patients with epileptic seizures. Whether late-onset seizures merit primary stroke prophylaxis is not known, and more information on stroke risk is needed for the planning of RCTs. We performed a case-control study based on Swedish national registers to quantify the risk of stroke after epileptic seizures.

Methods: Cases ≤100 years of age with a first-ever stroke 2001-2009 were identified through the Swedish Stroke Register, and stroke-free controls (matched for age and sex) were obtained from the Population Register. The National Patient Register provided information on diagnostic codes for seizures, epilepsy and comorbidities. 123 105 stroke cases and 250 506 controls were included.

Results: Epileptic seizures prior to index stroke date were detected in 1559 (1.27 %) cases and 1806 (0.72 %) controls, yielding an odds ratio (95 % confidence interval) for stroke of 1.77 (1.65-1.89). ORs were similar in men and women, but higher below the age of 75. An onset of seizures in the year preceding stroke date resulted in a higher risk for stroke (OR = 2.21, 95 % CI = 1.79-2.72) compared to when more than 5 years had passed since the first seizure (OR = 1.57, 95 % CI = 1.43-1.72).

Conclusion: A history of epileptic seizures was associated with an increased risk of subsequent stroke. The risk seems to be particularly high in the first year following seizure diagnosis, which supports the notion that unexplained late-onset seizures may merit swift assessment of vascular risk profile. The nature of stroke prevention requires further study.