Further Examination of Post-Traumatic Amnesia and Post-Coma Disturbance as Non-Linear Predictors of Outcome After Head Injury

The relationship between early neurological variables and cognitive outcome was investigated in a group of 77 severely head-injured patients following C. Haslam et al. (1994). At the time of admission, patients were assessed on 7 neurological indices, including durations of post-traumatic amnesia (PTA) and post-coma disturbance (PCD), the latter defined as the period between emergence from coma and end of PTA. PTA and PCD were transformed to address their non-linearity. Two years later, patients underwent examination on selected psychological measures. Recent memory was best predicted by transformed PTA, and speed of information processing was best predicted by transformed PCD. Prediction of both psychological factors was also improved by taking into account surgical evacuation of an extradural hematoma. Findings are consistent with research demonstrating the utility of transformed variables and PCD in prediction of cognitive outcome.