A comparative study on assessment procedures and metric properties of two scoring systems of the Coma Recovery Scale-Revised items: standard and modified scores

Objective: The study compared the metric characteristics (discriminant capacity and factorial structure) of two different methods for scoring the items of the Coma Recovery Scale-Revised and it analysed scale scores collected using the standard assessment procedure and a new proposed method. Design: Cross sectional design/methodological study. Setting: Inpatient, neurological unit. Participants: A total of 153 patients with disorders of consciousness were consecutively enrolled between 2011 and 2013. Intervention: All patients were assessed with the Coma Recovery Scale-Revised using standard (rater 1) and inverted (rater 2) procedures. Main outcome measures: Coma Recovery Scale-Revised score, number of cognitive and reflex behaviours and diagnosis. Results: Regarding patient assessment, rater 1 using standard and rater 2 using inverted procedures obtained the same best scores for each subscale of the Coma Recovery Scale-Revised for all patients, so no clinical (and statistical) difference was found between the two procedures. In 11 patients (7.7%), rater 2 noted that some Coma Recovery Scale-Revised codified behavioural responses were not found during assessment, although higher response categories were present. A total of 51 (36%) patients presented the same Coma Recovery Scale-Revised scores of 7 or 8 using a standard score, whereas no overlap was found using the modified score. Unidimensionality was confirmed for both score systems. Conclusion: The Coma Recovery Scale Modified Score showed a higher discriminant capacity than the standard score and a monofactorial structure was also supported. The inverted assessment procedure could be a useful evaluation method for the assessment of patients with disorder of consciousness diagnosis.