Inter-rater agreement on identification of electrographic seizures and periodic discharges in ICU EEG recordings

•Agreement was moderate among eight experts for labeling the location of seizures in 1 h epochs of continuous ICU EEG monitoring recordings.•Inter-rater agreement for labeling periodic discharges was considerably lower than for labeling seizures.•Agreement among experts was improved by the use of EEG education modules.

ObjectiveThis study investigated inter-rater agreement (IRA) among EEG experts for the identification of electrographic seizures and periodic discharges (PDs) in continuous ICU EEG recordings.MethodsEight board-certified EEG experts independently identified seizures and PDs in thirty 1-h EEG segments which were selected from ICU EEG recordings collected from three medical centers. IRA was compared between seizure and PD identifications, as well as among rater groups that have passed an ICU EEG Certification Test, developed by the Critical Care EEG Monitoring Research Consortium (CCEMRC).ResultsBoth kappa and event-based IRA statistics showed higher mean values in identification of seizures compared to PDs (k = 0.58 vs. 0.38; p < 0.001). The group of rater pairs who had both passed the ICU EEG Certification Test had a significantly higher mean IRA in comparison to rater pairs in which neither had passed the test.ConclusionsIRA among experts is significantly higher for identification of electrographic seizures compared to PDs. Additional instruction, such as the training module and certification test developed by the CCEMRC, could enhance this IRA.SignificanceThis study demonstrates more disagreement in the labeling of PDs in comparison to seizures. This may be improved by education about standard EEG nomenclature.