Prospective comparison of acute confusion severity with duration of post-traumatic amnesia in predicting employment outcome after traumatic brain injury

Background: Measurement of the duration of post-traumatic amnesia ( PTA) is common practice, serving as an important index of the severity of traumatic brain injury (TBI) and a predictor of functional outcome. However, controversy exists regarding the nature of PTA; some studies indicate that it is a confusional state with symptoms that extend beyond disorientation and amnesia. Objective: To evaluate the contribution of the severity of acute confusion 1 month after TBI to prediction of employment at 1 year after injury, comparing it with PTA duration. Methods: Prospective study involving 171 participants with complete data, who met the study criteria, from 228 consecutive TBI Model System admissions. Outcome measures included weekly administration of the Delirium Rating Scale-Revised-98 (DeIRS-R98) to measure the severity of acute confusion. Evaluations closest to 1 month after injury were used for study purposes. Duration of PTA was defined as the interval from injury until two consecutive Galveston Orientation and Amnesia Test scores of >= 76 were obtained within a period of 24-72 h. Univariable and multivariable logistic regression were used to predict employment status at 1 year after injury. Results: Age, education and DeIRS-R98 were significant predictors accounting for 34% of outcome variance. Individuals with greater confusion severity at 1 month after injury, older age and lower levels of education were less likely to be employed at 1 year after injury. Severity of confusion was more strongly associated with employment outcome (r(s) = 0.39) than was PTA duration (r(s) = 0.34). Conclusions: In addition to demographic indices, severity of acute confusion makes a unique contribution to predicting late outcome after TBI.