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

Abstract

Objectives 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. Design We retrospectively analyzed CRS-R subscale scores in hospital inpatients diagnosed with DoC 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 (i.e., frequency of occurrence = 0%) were also considered improbable. Setting Specialized DOC program and University hospital. Participants 1190 patients diagnosed with DoC (coma= 76, VS= 464, MCS= 586, EMCS= 64; 794 males; mean age= 43±20 years; traumatic etiology= 747; time post injury= 162±568 days). Interventions Not applicable. Main Outcome Measure(s) Impossible and improbable CRS-R subscore combinations. Results 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. Conclusions 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.

European Academy of Neurology guideline on the diagnosis of coma and other disorders of consciousness

“…Recommendation: Given that a mirror is a convenient bedside tool, it is recommended to always use it in DoC patients to diagnose visual pursuit ( low evidence, strong recommendation ). When testing for visual pursuit, it is necessary to rule out cortical blindness, damage to the optic nervous structures and central or peripheral oculomotor palsies . Regular reassessment is important because levels of consciousness may fluctuate rapidly .…”

“…using analytical approaches such as the revised Motor Behavior Tool or subjective approaches based on caregivers' collective intelligence such as the ‘DoC feeling’ . The examiner should be mindful of confounding factors such as cranial nerve palsies, central and peripheral causes of quadriplegia, severe spasticity, hypokinesia and bradykinesia, and hypertonus or hypotonus . PICO 4 Should the CRS‐R be used to diagnose the level of consciousness in patients with DoC? …”

“…language, memory, flexibility, attention) , intubation, sedation and the setting (e.g. presence or absence of relatives) should be taken into consideration . One study suggests that the presence of family members might increase chances of detecting visual responses .…”

The repetition of behavioral assessments in diagnosis of disorders of consciousness

“…Each subscale contains multiple items arranged in a hierarchical way, the highest item representing the most complex behavior. While some combinations of these items are impossible according to the scale guidelines, some improbable combinations might indicate specific impairments . The clinical diagnosis is thus based on the presence or absence of operationally defined behavioral responses to specific sensory stimuli (eg, if a response to command like “move your feet” is observed at least three times out of four trials, the patient is considered to be in MCS + ).…”

The Russian version of Coma Recovery Scale-revised - a standardized method for assessment of patients with disorders of consciousness

“…Пересмотренный вариант шкалы стал использоваться не только в США и англоязычных странах, но и в других регионах мира. В Европе были проведены валидационные исследования с переводом CRS-R и адаптацией шкалы на местные языки [17][18][19][20], шкала также была переведена и адаптирована в Китае [21].…”