A post-marketing safety surveillance study using a US health insurance claims database coupled with medical records review will be implemented to determine the risk of UR associated with exposure to AED polytherapy regimens containing EZG in a real-world setting. The risk of UR among epilepsy patients treated with EZG AED polytherapy will be compared to the risk among epilepsy patients treated with non-EZG AED polytherapy. In addition, both EZG and non-EZG AED polytherapy users will be described in terms of their demographic characteristics, concomitant AED use, co-morbidities, use of medications potentially associated with UR, and medical conditions pre-disposing to UR. Secondarily, off-label usage of EZG will be monitored and described. In addition, the risk of UR among epilepsy patients treated with non-EZG AED monotherapy will be determined.