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Coma Recovery Scale–Revised: Evidentiary Support for Hierarchical Grading of Level of Consciousness

      Abstract

      Objective

      To investigate the neurobehavioral pattern of recovery of consciousness as reflected by performance on the subscales of the Coma Recovery Scale–Revised (CRS-R).

      Design

      Retrospective item response theory (IRT) and factor analysis.

      Setting

      Inpatient rehabilitation facilities.

      Participants

      Rehabilitation inpatients (N=180) with posttraumatic disturbance in consciousness who participated in a double-blinded, randomized, controlled drug trial.

      Interventions

      Not applicable.

      Main Outcome Measures

      Scores on CRS-R subscales.

      Results

      The CRS-R was found to fit factor analytic models adhering to the assumptions of unidimensionality and monotonicity. In addition, subscales were mutually independent based on residual correlations. Nonparametric IRT reaffirmed the finding of monotonicity. A highly constrained confirmatory factor analysis model, which imposed equal factor loadings on all items, was found to fit the data well and was used to estimate a 1-parameter IRT model.

      Conclusions

      This study provides evidence of the unidimensionality of the CRS-R and supports the hierarchical structure of the CRS-R subscales, suggesting that it is an effective tool for establishing diagnosis and monitoring recovery of consciousness after severe traumatic brain injury.

      Keywords

      List of abbreviations:

      CFA (confirmatory factor analysis), CRS-R (Coma Recovery Scale–Revised), DOC (disorders of consciousness), EFA (exploratory factor analysis), IRT (item response theory), KSIRT (kernel density smoothing item response theory), SRMR (standardized root mean square of the residuals), TLI (Tucker-Lewis Index)
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