title: Psychometric properties of the disorders of consciousness scale.
abstract: OBJECTIVE
  To provide evidence for psychometric properties of the Disorders of Consciousness Scale (DOCS).
  
  
  METHODS
  Prospective observational cohort.
  
  
  METHODS
  Seven rehabilitation facilities.
  
  
  METHODS
  Patients (N=174) with severe brain injury.
  
  
  METHODS
  Not applicable.
  Initial analyses suggested eliminating 6 items to maximize psychometrics, resulting in the DOCS-25. The 25 items form a unidimensional hierarchy, rating scale categories are ordered, there are no misfitting items, and differential item functioning was not found according to sex, type of brain injury, veteran status, and days from onset. Person separation reliability (.91) indicates that the DOCS-25 is appropriate for individual patient measurement. Items are well targeted to the sample, with the difference between mean person and item calibrations less than 1 logit. DOCS-25 Rasch measures result in a 62% gain in relative precision over total raw scores. Internal consistency is very good (Cronbach α=.86); interrater agreement is excellent (intracIass correlation coefficient=.90) for both the DOCS-25 and the sensory subscales. The DOCS-25 total measure, but not subscale measures, correlates with the Glasgow Coma Scale and the Coma/Near-Coma Scales and distinguishes significantly between vegetative and minimally conscious states, indicating concurrent validity.
  
  
  CONCLUSIONS
  The DOCS-25 is psychometrically strong. It has excellent measurement precision and captures a broad range of patient function, which is critical for capturing recovery of consciousness. The sensory subscales are clinically informative but should not be reported as separate measures. The Keyform synthesizes clinical observations to visualize response patterns with potential for informing clinical decision-making. Future studies should determine sensitivity to change, examine issues of rater severity, and explore the usefulness of the Keyform in clinical practice.
authors.affiliation: Center for Innovation in Complex Chronic Healthcare and Research Service, Department of Veterans Affairs, Edward Hines, Jr. Veterans Affairs Hospital, Hines, IL; Department of Physical Medicine and Rehabilitation, Northwestern University Feinberg School of Medicine, Chicago, IL. Electronic address: Theresa.Pape@va.gov.
authors.forename: Theresa Louise-Bender
authors.initials: TL
authors.lastname: Pape
authors.affiliation: The School of Medicine & Health Sciences, The George Washington University, Washington, DC.
authors.forename: Trudy
authors.initials: T
authors.lastname: Mallinson
authors.affiliation: Marianjoy Rehabilitation Hospital, Wheaton, IL.
authors.forename: Ann
authors.initials: A
authors.lastname: Guernon
mesh_terms: D000203:Activities of Daily Living / Q000523:psychology*; D000328:Adult; D001930:Brain Injuries / Q000150:complications*; D003244:Consciousness Disorders / Q000145:classification / Q000209:etiology / Q000523:psychology* / Q000534:rehabilitation*; D003626:Data Display; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008960:Models, Psychological; D017063:Outcome Assessment, Health Care; D018458:Persistent Vegetative State / Q000145:classification; D025341:Principal Component Analysis; D011446:Prospective Studies; D011594:Psychometrics / Q000295:instrumentation* / Q000592:standards*; D020127:Recovery of Function; D015203:Reproducibility of Results
keywords: Brain injuries; Consciousness disorders; Outcome measures; Rehabilitation