Interrater agreement of EEG interpretation in comatose post cardiac arrest patients

Question: What is the interrater agreement of EEG interpretation in adult comatose post cardiac arrest patients using the American Clinical Neurophysiology Society (ACNS) standardized critical care EEG terminology? Methods: The EEG-data were obtained from patients included in the Target Temperature Management trial (TTM), an international, multicenter, clinical trial of temperature management in comatose cardiac arrest patients [N Engl J Med 2013]. In the TTM trial a routine EEG was performed in patients still comatose 12-36. h after rewarming.For this study, one EEG-specialist (IR) chose 20 EEGs, covering important aspects of the ACNS EEG terminology. Four EEG-specialists with different nationalities (Sweden: EW, Denmark: TWK, The Netherlands: AFvR and Switzerland: AOR) acquired the ACNS EEG terminology [J Clin Neurophys 2013;30:1-27] and studied a web-based training-module. The four EEG-specialists subsequently interpreted (blinded to patients' identity) the 20 EEGs, reporting the findings according to the ACNS EEG terminology. Percent agreement and Fleiss kappa values for every category in the terminology were calculated. Percent agreement was defined as the proportion of the 20 EEGs in which all interpreters reported identical findings. Results: There was 65% agreement on whether a rhythmic or periodic pattern was present or not (Kappa 0.44). If a rhythmic or periodic pattern was present there was 93% agreement on which type of pattern (periodic discharges, rhythmic delta activity, rhythmic spike-and-wave/polyspike-and-wave/sharp-and-slow-wave) (Kappa 0.65). Conclusions: Using the ACNS EEG terminology in adult comatose post cardiac arrest patients there was moderate agreement on the presence and type of periodic and rhythmic patterns.