Development of an online calculator for the prediction of seizure freedom following pediatric hemispherectomy using the Hemispherectomy Outcome Prediction Scale (HOPS)
Authors: Weil Alexander G. , Dimentberg Evan , Lewis Evan , Ibrahim George M. , Kola Olivia , Tseng Chi‐Hong , Chen Jia‐Shu , Lin Kao‐Min , Cai Li‐Xin , Liu Qing‐Zhu , Lin Jiu‐Luan , Zhou Wen‐Jing , Mathern Gary W. , Smyth Matthew D. , O'Neill Brent R. , Dudley Roy , Ragheb John , Bhatia Sanjiv , Delev Daniel , Ramantani Georgia , Zentner Josef , Wang Anthony C. , Dorfer Christian , Feucht Martha , Czech Thomas , Bollo Robert J. , Issabekov Galymzhan , Zhu Hongwei , Connolly Mary , Steinbok Paul , Zhang Jian‐Guo , Zhang Kai , Hidalgo Eveline Teresa , Weiner Howard L. , Wong‐Kisiel Lily , Lapalme‐Remis Samuel , Tripathi Manjari , Sarat Chandra Poodipedi , Hader Walter , Wang Feng‐Peng , Yao Yi , Champagne Pierre Olivier , Brunette‐Clément Tristan , Guo Qiang , Li Shao‐Chun , Budke Marcelo , Pérez‐Jiménez Maria Angeles , Raftopoulos Christian , Finet Patrice , Michel Pauline , Schaller Karl , Stienen Martin N. , Baro Valentina , Cantillano Malone Christian , Pociecha Juan , Chamorro Noelia , Muro Valeria L. , von Lehe Marec , Vieker Silvia , Oluigbo Chima , Gaillard William D. , Al Khateeb Mashael , Al Otaibi Faisal , Krayenbühl Niklaus , Bolton Jeffrey , Pearl Phillip L. , Fallah Aria 
Published: June 2023

Objectives

Although hemispheric surgeries are among the most effective procedures for drug‐resistant epilepsy (DRE) in the pediatric population, there is a large variability in seizure outcomes at the group level. A recently developed HOPS score provides individualized estimation of likelihood of seizure freedom to complement clinical judgement. The objective of this study was to develop a freely accessible online calculator that accurately predicts the probability of seizure freedom for any patient at 1‐, 2‐, and 5‐years post‐hemispherectomy.

Methods

Retrospective data of all pediatric patients with DRE and seizure outcome data from the original Hemispherectomy Outcome Prediction Scale (HOPS) study were included. The primary outcome of interest was time‐to‐seizure recurrence. A multivariate Cox proportional‐hazards regression model was developed to predict the likelihood of post‐hemispheric surgery seizure freedom at three time points (1‐, 2‐ and 5‐ years) based on a combination of variables identified by clinical judgment and inferential statistics predictive of the primary outcome. The final model from this study was encoded in a publicly accessible online calculator on the International Network for Epilepsy Surgery and Treatment (iNEST) website (https://hops‐calculator.com/).

Results

The selected variables for inclusion in the final model included the five original HOPS variables (age at seizure onset, etiologic substrate, seizure semiology, prior non‐hemispheric resective surgery, and contralateral fluorodeoxyglucose–positron emission tomography [FDG‐PET] hypometabolism) and three additional variables (age at surgery, history of infantile spasms, and magnetic resonance imaging [MRI] lesion). Predictors of shorter time‐to‐seizure recurrence included younger age at seizure onset, prior resective surgery, generalized seizure semiology, FDG‐PET hypometabolism contralateral to the side of surgery, contralateral MRI lesion, non‐lesional MRI, non‐stroke etiologies, and a history of infantile spasms. The area under the curve (AUC) of the final model was 73.0%.

Significance

Online calculators are useful, cost‐free tools that can assist physicians in risk estimation and inform joint decision‐making processes with patients and families, potentially leading to greater satisfaction. Although the HOPS data was validated in the original analysis, the authors encourage external validation of this new calculator.