Assessment of the Validity of the 2HELPS2B Score for Inpatient Seizure Risk Prediction

Question Is the 2HELPS2B inpatient seizure risk prediction tool valid for predicting electrographic seizures in an independent patient cohort and what duration of electroencephalogram (EEG) is needed to calculate it? Findings In this study of an independent cohort of continuous patients undergoing EEG, the 2HELPS2B calibration error and area under the curve were not statistically different from the foundational study. One hour of screening EEG is sufficient to stratify continuous EEG (cEEG) seizure risk and recommend cEEG monitoring duration. Meaning 2HELPS2B may be a useful tool to incorporate into the workflow of a cEEG service to maximize the efficiency of EEG resources and simplify communication regarding the clinical significance of EEG findings. Importance Seizure risk stratification is needed to boost inpatient seizure detection and to improve continuous electroencephalogram (cEEG) cost-effectiveness. 2HELPS2B can address this need but requires validation. Objective To use an independent cohort to validate the 2HELPS2B score and develop a practical guide for its use. Design, Setting, and Participants This multicenter retrospective medical record review analyzed clinical and EEG data from patients 18 years or older with a clinical indication for cEEG and an EEG duration of 12 hours or longer who were receiving consecutive cEEG at 6 centers from January 2012 to January 2019. 2HELPS2B was evaluated with the validation cohort using the mean calibration error (CAL), a measure of the difference between prediction and actual results. A Kaplan-Meier survival analysis was used to determine the duration of EEG monitoring to achieve a seizure risk of less than 5% based on the 2HELPS2B score calculated on first- hour (screening) EEG. Participants undergoing elective epilepsy monitoring and those who had experienced cardiac arrest were excluded. No participants who met the inclusion criteria were excluded. Main Outcomes and Measures The main outcome was a CAL error of less than 5% in the validation cohort. Results The study included 2111 participants (median age, 51 years; 1113 men [52.7%]; median EEG duration, 48 hours) and the primary outcome was met with a validation cohort CAL error of 4.0% compared with a CAL of 2.7% in the foundational cohort (P = .13). For the 2HELPS2B score calculated on only the first hour of EEG in those without seizures during that hour, the CAL error remained at less than 5.0% at 4.2% and allowed for stratifying patients into low- (2HELPS2B = 0; <5% risk of seizures), medium- (2HELPS2B = 1; 12% risk of seizures), and high-risk (2HELPS2B, >= 2; risk of seizures, >25%) groups. Each of the categories had an associated minimum recommended duration of EEG monitoring to achieve at least a less than 5% risk of seizures, a 2HELPS2B score of 0 at 1-hour screening EEG, a 2HELPS2B score of 1 at 12 hours, and a 2HELPS2B score of 2 or greater at 24 hours. Conclusions and Relevance In this study, 2HELPS2B was validated as a clinical tool to aid in seizure detection, clinical communication, and cEEG use in hospitalized patients. In patients without prior clinical seizures, a screening 1-hour EEG that showed no epileptiform findings was an adequate screen. In patients with any highly epileptiform EEG patterns during the first hour of EEG (ie, a 2HELPS2B score of >= 2), at least 24 hours of recording is recommended. This study assesses the validity of the 2HELPS2B score in predicting risk for electrographic seizures among patients undergoing electroencephalogram.