Frailty Measured by the Risk Analysis Index Predicts Non-home Discharge and Mortality After Resection in Refractory Epilepsy: Analysis of 1236 Patients from a Prospective Surgical Registry, 2012-2020

Introduction: Preoperative risk stratification of epilepsy surgery patients remains difficult. The Risk Analysis Index (RAI) is a robust frailty measurement tool for preoperative risk stratification. This study aimed to evaluate the discriminative threshold of preoperative RAI score for non-home discharge disposition (NHD) and mortality for epilepsy surgery patients in a multi-center prospective surgical registry.

Methods: Patients undergoing epilepsy surgery were queried from the American College of Surgeons – National Surgical Quality Improvement Program database (2012-2020) using diagnosis/procedure codes. Linear-by-linear trend tests were performed to assess RAI's relationsip with NHD and mortality. Discriminatory accuracy was assessed by C-statistics (with 95% confidence interval [CI]) in receiver operating characteristic curve analysis.

Results: Epilepsy surgeries (N=1236) were grouped into temporal lobe (60.4%, N=747) and non-temporal lobe (39.6%, N=489) procedures. Patients were stratified by RAI frailty tier: 76.5% robust (RAI 0-20), 16.2% normal (RAI 21-30), 6.6% frail (RAI 31-40), and 0.8% severely frail (RAI 41+). NHD rate was 18.0% and was positively associated with increasing RAI tier: 12.5% in robust, 34.0% in normal, 38.3% in frail, and 50.0% in severely frail (P < 0.001). RAI had robust predictive discrimination for NHD in overall cohort (C-statistic 0.71), temporal lobe (C-statistic 0.70) and non-temporal lobe (C-statistic 0.71) cohorts. Overall mortality rate was 2.7% and significantly associated with RAI frailty: 1.1% in robust, 8.0% in normal, 6.2% in frail, and 20.0% in severely frail (P < 0.001). RAI had excellent predictive discrimination for mortality in overall epilepsy surgery cohort (C-statistic 0.78) as well as temporal lobe (C-statistic 0.80) and non-temporal lobe (C-statistic 0.74) cohorts.

Conclusion : RAI frailty score predicts mortality and NHD after epilepsy surgery in patients with intractable epilepsy. This tool can translate to the bedside with a user-friendly calculator: https://nsgyfrailtyoutcomeslab.shinyapps.io/epilepsy/ . These findings hope to augment the risk stratification in the treatment of refractory epilepsy and provide an example for future studies.