Year, Volume, Issue, Page(s):10, 24, 3, 472-478
Study examined the ability of categories of post-traumatic amnesia (PTA) duration to predict 1-year outcomes after traumatic brain injury (TBI). Outcome measures included the Functional Independence Measure, the Supervision Rating Scale, the Glasgow Outcome Scale-Extended, and employment status. Using the data from 5,250 subjects enrolled in the TBI Model System database, the duration of PTA that predicts 1-year outcomes was calculated. Logistic regression was used to determine whether a single predictive threshold value existed. Classification and regression tree analysis then determined whether multiple threshold values existed. The area under the receiver operating characteristic curve and percentage correct classification were also calculated to discriminate classification accuracy and choose the best predictive thresholds. A single threshold value of PTA days was identified for all variables. At 1 year, PTA that extended into week 7 after injury predicted total, motor, and cognitive Functional Independence Measure scores. One-year employment and global outcomes were predicted by PTA extending into week 4 after injury. Independent living was predicted by PTA extending into the 8th week after injury. The authors conclude that determining the presence of PTA at weekly intervals can efficiently determine TBI injury severity while providing meaningful precision when used in research and clinical outcome prediction.