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From the James A. Haley VAMC (R.N.-R.), Tampa, FL; Methodist Rehabilitation Center (R.N.-R., S.A.Y., C.C.E.) and University of Mississippi Medical Center (R.N.-R., S.A.Y., C.C.E.), Jackson, MI; TIRR Memorial Hermann and Baylor College of Medicine (M.S.), Houston, TX; and University of Arkansas for Medical Sciences (T.G.N.), Little Rock, AR.
Address correspondence and reprint requests to Dr. Risa Nakase-Richardson, James A. Haley Veterans Hospital, MH & BS/Polytrauma (116B), 13000 Bruce B. Downs Blvd., Tampa, FL 33612 risa.richardson{at}va.gov
Background: Guidelines for defining the minimally conscious state (MCS) specify behaviors that characterize emergence, including "reliable and consistent" functional communication (accurate yes/no responding). Guidelines were developed by consensus because of lack of empirical data.
Objective: To evaluate the utility of the operational threshold for emergence from posttraumatic MCS, by determining yes/no accuracy to questions of varied difficulty, including simple orientation questions, using all items from the Yes/No Subscale of the Mississippi Aphasia Screening Test.
Method: Prospective observational study of a cohort of responsive patients recovering from traumatic brain injury in an acute inpatient brain injury rehabilitation program.
Results: Of the 629 observations from 144 participants, name recognition was the easiest yes/no question, with nonconfused individuals responding with 100% accuracy, whereas only 75% to 78% of confused participants on initial evaluation answered this question correctly. Generalized Estimating Equations analysis revealed that confused participants were more likely to respond inaccurately to all yes/no questions. Nonconfused participants had a reduction in odds of inaccuracy ranging from 45.6% to 99.7% (p = 0.001 to 0.02) depending on the type of yes/no question.
Conclusions: Accuracy for simple orientation yes/no questions remains challenging for responsive patients in early recovery from traumatic brain injury. Although name recognition questions are relatively easier than other types of yes/no questions, including situational orientation questions, confused patients still may answer these incorrectly. Results suggest the operational threshold for yes/no response accuracy as a diagnostic criterion for emergence from the minimally conscious state should be revisited, with particular consideration of the type of yes/no questions and the requisite accuracy threshold for responses.
Abbreviations: CI = confidence interval; CRS = Coma Recovery Scale; DDX = diagnostic criteria for delirium; DRS = Disability Rating Scale; DRS-ADL = Disability Rating Scale self-care items; DSM = Diagnostic and Statistical Manual of Mental Disorders; GCS = Glasgow Coma Scale; GEE = Generalized Estimating Equations; ID = item difficulty; LOS = length of stay; MAST = Mississippi Aphasia Screening Test; MAST-YN = Mississippi Aphasia Screening Test Yes/No Accuracy Subscale; MCS = minimally conscious state; PTA = posttraumatic amnesia; TBI = traumatic brain injury.
This study was part of the Traumatic Brain Injury Model System of Mississippi funded by the National Institute on Disability Rehabilitation and Research (H133A020514 Dr. Risa Nakase-Richardson, PI).
Disclosure: Author disclosures are provided at the end of the article.
Portions of the data were presented at the 2008 American Congress of Rehabilitation Meeting in Toronto, Canada.
Received February 2, 2009. Accepted in final form July 17, 2009.
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