Interrater reliability of visually evaluated high frequency oscillations.
High frequency oscillations (HFOs) and interictal epileptiform discharges (IEDs) have been shown to be markers of epileptogenic regions. However, there is currently no 'gold standard' for identifying HFOs. Accordingly, we aimed to formally characterize the interrater reliability of HFO markings to validate the current practices.



A morphology detector was implemented to detect events (candidate HFOs, lower-threshold events, and distractors) from the intracranial EEG (iEEG) of ten patients. Six electroencephalographers visually evaluated these events for the presence of HFOs and IEDs. Interrater reliability was calculated using pairwise Cohen's Kappa (κ) and intraclass correlation coefficients (ICC).



The HFO evaluation distributions were significantly different for most pairs of reviewers (p<0.05; 11/15 pairs). Interrater reliability was poor for HFOs alone (κmean=0.403; ICC=0.401) and HFO+IEDs (κmean=0.568; ICC=0.570).



The current practice of using two visual reviewers to identify HFOs is prone to bias arising from the poor agreement between reviewers, limiting the extrinsic validity of studies using these markers.



The poor interrater reliability underlines the need for a framework to reconcile the important findings of existing studies. The present epoched design is an ideal candidate for the implementation of such a framework.
Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada; Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, AB, Canada. Electronic address: amspring@ucalgary.ca.
Aaron M
AM
Spring
Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada; Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, AB, Canada. Electronic address: djpittman@me.com.
Daniel J
DJ
Pittman
Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada. Electronic address: Yahya.Agha-Khani@albertahealthservices.ca.
Yahya
Y
Aghakhani
Department of Medicine, University of Alberta, Edmonton, AB, Canada. Electronic address: jirsch@ualberta.ca.
Jeffrey
J
Jirsch
Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada. Electronic address: pillay@ucalgary.ca.
Neelan
N
Pillay
Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada; Department of Paediatrics, University of Calgary, Calgary, AB, Canada. Electronic address: Luis.Bello@albertahealthservices.ca.
Luis E
LE
Bello-Espinosa
Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada. Electronic address: colin.josephson@gmail.com.
Colin
C
Josephson
Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada; Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, AB, Canada; Department of Radiology, University of Calgary, Calgary, AB, Canada. Electronic address: pfederic@ucalgary.ca.
Paolo
P
Federico
D032921:Consensus; D004569:Electroencephalography / Q000379:methods / Q000592:standards*; D004827:Epilepsy / Q000175:diagnosis*; D006801:Humans; D015588:Observer Variation
High frequency oscillations; Interictal epileptiform discharges; Interrater reliability; Interrater variability; Intracranial electroencephalography; Spikes