Abstract:
Previous investigations have studied the association of early neuropsychological test performance with late outcome in patients who were initially evaluated during inpatient rehabilitation. However, in these previous investigations, neuropsychological test findings have been confounded with patient injury severity. Neuropsychological assessment was performed at resolution of PTA and PTA duration is a well-recognized index of injury severity. Clinical experience would suggest that a patient who reaches a given level of neuropsychological functioning at one month post injury will have a better long term outcome than another patient who takes 3 months to reach the same level of neuropsychological functioning. By basing timing of testing on an index of injury severity (PTA duration), previous investigations have obscured this important issue. In the proposed investigation, timing of testing is based on time post-injury rather than PTA duration, thereby avoiding the confounding of injury severity with timing of neuropsychological assessment. Through this methodology, we hope to demonstrate an even stronger association between early neuropsychological functioning and late functional outcome; a finding that could support early neuropsychological assessment at a fixed time post injury as a standard of care to facilitate prediction of late outcome, treatment planning and patient and family education. This project has three hypotheses:

Hypothesis 1. The majority of patient (>50%) admitted to the acute rehabilitation setting at one month after TBI (+/- 2 weeks) will be able to complete a brief battery of formal neuropsychological tests with the administration time of less than or equal to 75 minutes. The neuropsychological test battery is compromised of the following measures: California Verbal Learning Test II Standard Form (CVLT-II), Galveston Orientation and Amnesia Test (GOAT), Trail Making Test-Reitan (TMT), Symbol Digit Modalities Test (SDMT), Grooved Pegboard Test (GPT), Verbal Fluency (FAS and Animal Naming), Wechsler Test of Adult Reading (WTAR), Wisconsin Card Sorting Test-64 item version (WCST-64).

Hypothesis 2. Measures of severity of cognitive impairment will be significantly correlated with measures of initial injury severity and degree of functional disability at one-year post TBI. Functional measures/variables include: DRS, FIM, Supervision Rating Scale, Satisfaction with Life Scale, GOS-E, length of stay (medical and rehab), charges (medical and rehab), revised trauma score at hospital admission, acute operations and non-cognitive FIM score at rehab admission. These data will be taken from the TBI Model System database (Forms I and II).

Hypothesis 3. A Cognitive Severity Impairment (CSI) index, to be developed as part of the project, will make a unique prediction to total length of stay (medical/rehab) and hospital (medical/rehab) charges relative to other known predictors.

Collaborating centers participating in this project are: Alabama, Michigan, Mississippi, New Jersey, New York, Pennsylvania (Pittsburgh) and Texas. Lead center is JFK Johnson Rehabilitation Institute in New Jersey. Principal investigator is Kathleen Kalmar, Ph.D. Formal data collection was started at the beginning of July 2004 at all centers. De-identified data are to be submitted to the lead center by mid-September 2004 for purposes of analysis of data integrity and preliminary exploration of possible trends in the data.