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

Abstract

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. 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. 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. 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.