First unprovoked seizures among soldiers recruited to the Israeli Defense Forces during 10 consecutive years: A population-based study

Objective: The management of patients after a first unprovoked seizure (FUS) can benefit from stratification of the average 50% risk for further seizures. We characterized subjects with FUSs, out of a large generally healthy homogenous population of soldiers recruited by law to the Israeli Defense Forces, to investigate the role of the type of service, as a trigger burden surrogate, in the risk for additional seizures.Methods: Soldiers recruited between 2005 and 2014, who experienced an FUS during their service, were identified from military records. Subjects with a history of epilepsy or lack of documentation of FUS characteristics were excluded from the study. Data on demographics and military service and medical details were extracted for the eligible soldiers.Results: Of 816 252 newly recruited soldiers, representing 2 138 000 person-years, 346 had an FUS, indicating an incidence rate of 16.2 per 100 000 person-years. The FUS incidence rate was higher in combat versus noncombat male and female soldiers (p < .0001). Most subjects (75.7%) were prescribed antiseizure medications (ASMs), and 29.2% had additional seizures after the FUS. Service in combat units, abnormal magnetic resonance imaging, and being prescribed ASMs were correlated with a lower risk of having multiple seizures (95% confidence interval [CI] = .48-.97, .09-.86, .15-.28, respectively). On multivariate analysis, service in combat units (odds ratio [OR] = .48 for seizure recurrence, 95% CI = .26-.88) and taking medications (OR = .46, 95% CI = .24-.9) independently predicted not having additional seizures.Significance: FUS incidence rate was higher in combat soldiers, but they had a twofold lower risk of additional seizures than noncombat soldiers, emphasizing the value of strenuous triggers as negative predictors for developing epilepsy. This suggests a shift in the perception of epilepsy from a "yes or no" condition to a continuous trend of predisposition to seizures, warranting changes in the ways etiologies of epilepsy are weighted and treatments are delivered.