Inter-rater reliability of the Full Outline of UnResponsiveness score and the Glasgow Coma Scale in critically ill patients: a prospective observational study

INTRODUCTION The Glasgow Coma Scale (GCS) is the most widely used scoring system for comatose patients in intensive care. Limitations of the GCS include the impossibility to assess the verbal score in intubated or aphasic patients, and an inconsistent inter-rater reliability. The FOUR (Full Outline of UnResponsiveness) score, a new coma scale not reliant on verbal response, was recently proposed. The aim of the present study was to compare the inter-rater reliability of the GCS and the FOUR score among unselected patients in general critical care. A further aim was to compare the inter-rater reliability of neurologists with that of intensive care unit (ICU) staff. METHODS In this prospective observational study, scoring of GCS and FOUR score was performed by neurologists and ICU staff on 267 consecutive patients admitted to intensive care. RESULTS In a total of 437 pair wise ratings the exact inter-rater agreement for the GCS was 71%, and for the FOUR score 82% (P = 0.0016); the inter-rater agreement within a range of +/- 1 score point for the GCS was 90%, and for the FOUR score 92% (P = ns.). The exact inter-rater agreement among neurologists was superior to that among ICU staff for the FOUR score (87% vs. 79%, P = 0.04) but not for the GCS (73% vs. 73%). Neurologists and ICU staff did not significantly differ in the inter-rater agreement within a range of +/- 1 score point for both GCS (88% vs. 93%) and the FOUR score (91% vs. 88%). CONCLUSIONS The FOUR score performed better than the GCS for exact inter-rater agreement, but not for the clinically more relevant agreement within the range of +/- 1 score point. Though neurologists outperformed ICU staff with regard to exact inter-rater agreement, the inter-rater agreement of ICU staff within the clinically more relevant range of +/- 1 score point equalled that of the neurologists. The small advantage in inter-rater reliability of the FOUR score is most likely insufficient to replace the GCS, a score with a long tradition in intensive care.