Interrater reliability of Engel, International League Against Epilepsy, and McHugh seizure outcome classifications following vagus nerve stimulator implantation.

Object: Interrater reliability as measured by the kappa (κ) statistic is a widely used and valuable tool to measure the robustness of a scoring system. Seizure frequency reduction is a central outcome measure following vagus nerve stimulation (VNS). A specific VNS scoring system has been proposed by McHugh, but its interrater reliability has not been tested.