Prior hospitalization for stroke, diabetes, myocardial infarction, and subsequent risk of unprovoked seizures

Summary Purpose:  To study diabetes, acute myocardial infarction, and stroke as risk factors for unprovoked seizures in a population-based cohort with incident cases of epilepsy. Methods:  In this nested case–control study, the cases were 933 patients with newly diagnosed unprovoked seizures from the Stockholm Incidence Registry of Epilepsy. Controls, in total 6,039—matched for gender, year of diagnosis, and catchment area—were randomly selected from the register of the Stockholm County population. A history of diabetes, myocardial infarction, and stroke preceding the date of onset of seizure was determined by search of the Swedish Hospital Discharge Registry. Odds ratios (ORs) were calculated to assess the risk of developing unprovoked seizures after hospital admission for any of these diagnoses. Results:  The age-adjusted OR (95% confidence interval, 95% CI) for unprovoked seizures after a discharge diagnosis of diabetes was 1.9 (95% CI 1.4–2.8) and after acute myocardial infarction 1.7 (95% CI 1.0–2.9). The OR was 9.4 (95% CI 6.7–13.1) after cerebral infarction, 7.2 (95% CI 3.9–13.6) after intracerebral hemorrhage, 7.2 (95% CI 2.9–18.1) after subarachnoid hemorrhage, and 3.2 (95% CI 1.9–5.5) after transient ischemic attack. The population attributable risk percent (PAR%) was <2% for each of the diagnoses except for cerebral infarction, for which the PAR% was 9%. Taken together the studied diagnoses accounted for 15% of the incident cases of unprovoked seizures. Discussion:  As previously known, the risk for unprovoked seizures and epilepsy after a cerebral infarction was highest the first year after the infarction. This risk remained substantial >7 years after a diagnosis of cerebral infarction.