Inter-rater reliability and clinical utility of the BASED score in infantile epileptic spasms syndrome
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T P Cramer1, B Johnsen1,2, V S Hansen1
1Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark.
Insights
The Burden of Amplitudes and Epileptiform Discharges (BASED) score improves interrater reliability for diagnosing infantile epileptic spasms syndrome (IESS) hypsarrhythmia. This new scoring method shows higher accuracy than traditional EEG analysis.
Area of Science:
- Pediatric Neurology
- Electroencephalography (EEG)
- Epilepsy Syndromes
Background:
- Hypsarrhythmia is the characteristic EEG pattern in infantile epileptic spasms syndrome (IESS).
- Traditional hypsarrhythmia scoring lacks clear definitions, leading to poor interrater reliability (IRR).
- Objective assessment is needed to improve diagnostic consistency for IESS.
Purpose of the Study:
- To validate the Burden of Amplitudes and Epileptiform Discharges (BASED) score for hypsarrhythmia in children.
- To compare the IRR of the BASED score against traditional EEG scoring methods.
- To assess the correlation between EEG findings and clinical outcomes.
Main Methods:
- Retrospective analysis of 20 pediatric patients' EEGs before and after treatment.
- Three neurophysiologists independently scored EEGs using traditional methods and the BASED score.
- Interrater reliability was calculated using Gwet's AC1 statistic.
Main Results:
- The BASED score achieved significantly higher IRR (0.88) compared to traditional scoring (0.62) for diagnosing epileptic encephalopathy (p=0.01).
- Complete agreement on EEG interpretation was higher with the BASED score (36/40 EEGs) versus traditional methods (28/40 EEGs) (p=0.048).
- The BASED score showed substantial agreement for its individual components and correlated well with clinical remission.
Conclusions:
- The BASED score offers superior interrater reliability for hypsarrhythmia assessment in IESS.
- This validated scoring system demonstrates strong concordance with clinical course, supporting its diagnostic utility.
- The BASED score represents a significant advancement in the objective evaluation of hypsarrhythmia.
Objective:
Hypsarrhythmia is the classical EEG pattern of children with infantile epileptic spasms syndrome (IESS). Multifocal spikes, slow waves of large amplitude, and chaoticity are its main characteristics, but these lack clear definitions, and the interrater reliability (IRR) is poor. The aim of this study was to substantiate the use of the Burden of Amplitudes and Epileptiform Discharges (BASED) score for children with hypsarrhythmia on initial EEG and to compare the IRR to traditional scoring.
Methods:
We identified before and after treatment EEGs from 20 consecutive patients from a local database. Clinical remission was defined as the remission of spasms. Three experienced Danish neurophysiologists, blinded to clinical information, rated each EEG separately using traditional visual analysis and the BASED score. A BASED score ≥4 and any hypsarrhythmic pattern were considered consistent with an epileptic encephalopathy. IRR was estimated using Gwet's AC1.
Results:
IRR for scoring an epileptic encephalopathy was significantly better when using the BASED score compared with the traditional method (0.88 vs. 0.62, p = 0.01). Complete agreement was observed in 36 out of 40 EEGs using the BASED score vs. 28 out of 40 using the traditional method (Fisher's exact test: p = 0.048). IRR was near perfect or substantial in all but one of the individual components of the BASED score. Clinical remission was seen in 14 out of 19 patients, and the clinical course was consistent with EEG in 18 out of 19 patients using the BASED score and in 16 out of 19 patients using the traditional method (Fisher's exact test: p = 0.60).
Significance:
The BASED score demonstrated very high interrater reliability, exceeding that of traditional hypsarrhythmia scoring. It also corresponded closely with the clinical course, supporting its validity.
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