Prediction of return to productivity after severe traumatic brain injury: investigations of optimal neuropsychological tests and timing of assessment.

OBJECTIVES: (1) To examine predictive validity of global neuropsychological performance, and performance on timed tests (controlling for manual motor function) and untimed tests, including attention, memory, executive function, on return to productivity at 1 year after traumatic brain injury (TBI). (2) To compare predictive validity at 8 weeks versus 5 months postinjury. (3) To examine predictive validity of early degree of recovery (8wk-5mo postinjury) for return to productivity.

DESIGN: Longitudinal, within subjects.

SETTING: Inpatient neurorehabilitation and community.

PARTICIPANTS: Patients (N=63) with moderate to severe TBI.

INTERVENTIONS: Not applicable.

PRIMARY OUTCOME: return to productivity at 1 year postinjury. Primary predictors: neuropsychological composite scores. Control variables: posttraumatic amnesia, acute care length of stay (LOS), Glasgow Coma Scale score, age, and estimated premorbid intelligence quotient.

RESULTS: Return to productivity was significantly correlated with global neuropsychological performance at 5 months postinjury (P<.05) and showed a trend toward significance at 8 weeks. Performance on the untimed composite score, and more specifically executive and memory functions, mirrored this pattern. Logical Memory performance significantly predicted return to productivity, but not other memory tests. Timed tests showed no significance or trend at either time point. Early degree of recovery did not predict return to productivity. Among control variables, only acute care LOS was predictive of return to productivity.

CONCLUSIONS: Findings validate utility of early neuropsychological assessment for predicting later return to productivity. They also provide more precise information regarding the optimal timing and test type: results support testing at 5 months postinjury on untimed tests (memory and executive function), but not simple attention or speed of mental processing. Findings are discussed with reference to previous literature.