The reliability of the Glasgow Coma Scale: a systematic review
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The Glasgow Coma Scale (GCS) provides a structured method for assessment of the level of consciousness. Its derived sum score is applied in research and adopted in intensive care unit scoring systems. Controversy exists on the reliability of the GCS. The aim of this systematic review was to summarize evidence on the reliability of the GCS.
A literature search was undertaken in MEDLINE, EMBASE and CINAHL. Observational studies that assessed the reliability of the GCS, expressed by a statistical measure, were included. Methodological quality was evaluated with the consensus-based standards for the selection of health measurement instruments checklist and its influence on results considered. Reliability estimates were synthesized narratively.
We identified 52 relevant studies that showed significant heterogeneity in the type of reliability estimates used, patients studied, setting and characteristics of observers. Methodological quality was good (n = 7), fair (n = 18) or poor (n = 27). In good quality studies, kappa values were ≥0.6 in 85 %, and all intraclass correlation coefficients indicated excellent reliability. Poor quality studies showed lower reliability estimates. Reliability for the GCS components was higher than for the sum score. Factors that may influence reliability include education and training, the level of consciousness and type of stimuli used.
Only 13 % of studies were of good quality and inconsistency in reported reliability estimates was found. Although the reliability was adequate in good quality studies, further improvement is desirable. From a methodological perspective, the quality of reliability studies needs to be improved. From a clinical perspective, a renewed focus on training/education and standardization of assessment is required.
KeywordsGlasgow Coma Scale Glasgow Coma Score Grading scales Reliability Reproducibility of results Systematic review
The authors would like to thank Sir Graham Teasdale, Emeritus Professor of Neurosurgery, University of Glasgow, UK, for the valuable discussions and very helpful contribution throughout the course of this work. This work was in part supported by the Framework 7 program of the European Union in the context of CENTER-TBI (Grant Number 602150-2).
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Conflicts of interest
The authors declare that they have no conflict of interest.
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