An examination of the heterogeneity of cognitive outcome following severe to extremely severe traumatic brain injury

Objective: The current study aimed to explore neuropsychological outcomes in the initial recovery period following severe to extremely severe traumatic brain injury (TBI). Method: Using reliable change statistics, individuals were categorized as demonstrating cognitive improvement, stability or decline based on performance on 11 neuropsychological measures relative to scores returned during an initial assessment conducted in the acute post-injury stage. The study explored injury, demographic, and other variables as predictors of group membership. A total of 79 individuals were recruited from retrospective neuropsychological records between 2009 and 2017. Individuals were assessed on two occasions as per routine clinical practice. Approximately 10% of subjects sustained a severe TBI, 52% sustained a very severe TBI, and 38% sustained an extremely severe TBI. Results: Of the 79 participants, two individuals (2.5%) demonstrated cognitive decline, 28 individuals (35.4%) demonstrated cognitive stability, and 49 individuals (62%) demonstrated cognitive improvement. A binary logistic regression indicated that length of post-traumatic amnesia, as a categorical variable, was significantly predictive of group membership in that those with extremely severe TBIs were more likely to show improvement over time. Additionally, high levels of stress at review assessment, as measured on the Depression Anxiety Stress Scales, was predictive of membership in the cognitive improvement group. Conclusion: The results highlighted the heterogeneity of recovery in the initial recovery period following severe to extremely severe TBI and have the potential to inform clinical advice regarding outcome trajectories.