Detection and Interpretation of Impossible and Improbable Coma Recovery Scale-Revised Scores

Published:March 01, 2016DOI:



      To determine the frequency with which specific Coma Recovery Scale-Revised (CRS-R) subscale scores co-occur as a means of providing clinicians and researchers with an empirical method of assessing CRS-R data quality.


      We retrospectively analyzed CRS-R subscale scores in hospital inpatients diagnosed with disorders of consciousness (DOCs) to identify impossible and improbable subscore combinations as a means of detecting inaccurate and unusual scores. Impossible subscore combinations were based on violations of CRS-R scoring guidelines. To determine improbable subscore combinations, we relied on the Mahalanobis distance, which detects outliers within a distribution of scores. Subscore pairs that were not observed at all in the database (ie, frequency of occurrence=0%) were also considered improbable.


      Specialized DOC program and university hospital.


      Patients diagnosed with DOCs (N=1190; coma: n=76, vegetative state: n=464, minimally conscious state: n=586, emerged from minimally conscious state: n=64; 794 men; mean age, 43±20y; traumatic etiology: n=747; time postinjury, 162±568d).


      Not applicable.

      Main Outcome Measure

      Impossible and improbable CRS-R subscore combinations.


      Of the 1190 CRS-R profiles analyzed, 4.7% were excluded because they met scoring criteria for impossible co-occurrence. Among the 1137 remaining profiles, 12.2% (41/336) of possible subscore combinations were classified as improbable.


      Clinicians and researchers should take steps to ensure the accuracy of CRS-R scores. To minimize the risk of diagnostic error and erroneous research findings, we have identified 9 impossible and 36 improbable CRS-R subscore combinations. The presence of any one of these subscore combinations should trigger additional data quality review.


      List of abbreviations:

      CRS-R (Coma Recovery Scale-Revised), DOC (disorder of consciousness), EMCS (emerged from minimally conscious state), MCS (minimally conscious state), VS (vegetative state)
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        • Laureys S.
        • Celesia G.G.
        • Cohadon F.
        • et al.
        Unresponsive wakefulness syndrome: a new name for the vegetative state or apallic syndrome.
        BMC Med. 2010; 8: 68
      1. Medical aspects of the persistent vegetative state (1). The Multi-Society Task Force on PVS.
        N Engl J Med. 1994; 330: 1499-1508
        • Giacino J.T.
        • Ashwal S.
        • Childs N.
        • et al.
        The minimally conscious state: definition and diagnostic criteria.
        Neurology. 2002; 58: 349-353
        • Schnakers C.
        • Vanhaudenhuyse A.
        • Giacino J.
        • et al.
        Diagnostic accuracy of the vegetative and minimally conscious state: clinical consensus versus standardized neurobehavioral assessment.
        BMC Neurol. 2009; 9: 35
        • Stender J.
        • Kupers R.
        • Rodell A.
        • et al.
        Quantitative rates of brain glucose metabolism distinguish minimally conscious from vegetative state patients.
        J Cereb Blood Flow Metab. 2015; 35: 58-65
        • Giacino J.
        • Kalmar K.
        • Whyte J.
        The JFK Coma Recovery Scale-Revised: measurement characteristics and diagnostic utility.
        Arch Phys Med Rehabil. 2004; 85: 2020-2029
        • American Congress of Rehabilitation Medicine
        • Brain Injury-Interdisciplinary Special Interest Group
        • Disorders of Consciousness Task Force
        • et al.
        Assessment scales for disorders of consciousness: evidence-based recommendations for clinical practice and research.
        Arch Phys Med Rehabil. 2010; 91: 1795-1813
        • Bodien Y.G.
        • Carlowicz C.A.
        • Chatelle C.
        • Giacino J.T.
        Sensitivity and specificity of the Coma Recovery Scale-Revised total score in detection of conscious awareness.
        Arch Phys Med Rehabil. 2016; 97: 490-492.e1
        • La Porta F.
        • Caselli S.
        • Ianes A.B.
        • et al.
        Can we scientifically and reliably measure the level of consciousness in vegetative and minimally conscious States? Rasch analysis of the coma recovery scale-revised.
        Arch Phys Med Rehabil. 2013; 94: 527-535.e1
        • Gerrard P.
        • Zafonte R.
        • Giacino J.T.
        Coma Recovery Scale-Revised: evidentiary support for hierarchical grading of level of consciousness.
        Arch Phys Med Rehabil. 2014; 95: 2335-2341
        • Mahalanobis P.
        On the generalized distance in statistics.
        Proceedings of the National Institute of Science of India. 1936; 12: 49-55
        • Schnakers C.
        • Majerus S.
        • Giacino J.
        • et al.
        A French validation study of the Coma Recovery Scale-Revised (CRS-R).
        Brain Inj. 2008; 22: 786-792
        • Løvstad M.
        • Frøslie K.F.
        • Giacino J.T.
        • Skandsen T.
        • Anke A.
        • Schanke A.K.
        Reliability and diagnostic characteristics of the JFK coma recovery scale-revised: exploring the influence of rater's level of experience.
        J Head Trauma Rehabil. 2010; 25: 349-356

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      • Correction
        Archives of Physical Medicine and RehabilitationVol. 99Issue 12
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          In the article by Chatelle et al, Detection and Interpretation of Impossible and Improbable Coma Recovery Scale-Revised Scores, published in Archives of Physical Medicine and Rehabilitation 2016;97:1295-300 ( 10.1016/j.apmr.2016.02.009 ), Appendix 1 reports subscore combinations that are “impossible” to obtain if CRS-R administration and guidelines are followed properly. However, the authors have determined that these subscore combinations do not violate CRS-R administration or scoring rules. Consequently, the authors have re-analyzed all subscale scores, including the nine subscore combinations previously listed as “impossible,” using the methods described in the article.
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