Patterns of Performance on the Paced Auditory Serial Addition Test (PASAT) as a Predictor of Brain Injury Severity: Consideration of Dyad and Skipping Scores



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Objective: The present study was designed to investigate the relationship between patterns of performance on the PASAT and severity of injury variables when demographic variables were taken into account. Participants and Methods: Eighty-one patients with mild, moderate and severe traumatic brain injury (TBI) were selected from a larger group of patients that had been consecutively admitted to Ben Taub General Hospital (BTGH) Level 1 trauma center. Patients were evaluated at 3 months post-injury to determine functional outcome, determined by their performance on the PASAT. Performance scores were calculated for correct response dyad (CRD) and the newly developed modified score of intermittent performance (M-ScIP). Multiple hierarchical linear and logistic regression analyses were conducted to determine the relationship between 1) PASAT scores and injury severity, and 2) patterns of performance and injury severity variables, all while accounting for demographic variables. A cluster analysis was conducted to assign each patient into one of two cluster groupings, based on their relative patterns of performance across PASAT trials. These analyses were conducted separately for CRD and M-ScIP scores. Results: Injury severity, measured by best day 1 Glasgow Coma Scale (BD1 GCS), was positively related to CRDs and negatively related to M-ScIP scores. M-ScIP scores were also negatively related to education. After an initial cluster analysis was conducted separately for CRD and M-ScIP scores, the relationship between the respective clusters and injury severity/demographic variables was assessed. Only the BD1 GCS was a significant predictor of patient cluster assignment for CRD clusters. None of the predictor variables were related to the M-ScIP clusters.
Conclusion: Only the BD1 GCS consistently emerged as a significant predictor of CRD and M-ScIP PASAT scores and patterns of CRD scores across the PASAT trials. The small sample size used in this study limited the number of clusters that could be generated from patient test scores, which may have prevented the emergence of significant findings for the M-ScIP cluster analysis. Additionally, the data for this study was obtained from patients that were able to complete the PASAT at 3 months post injury, which suggests that they may have been a less-severely injury subset of the full patient sample. The use of this uncharacteristically homogeneous population may have suppressed the emergence of other significant relationships between predictor and outcome variables that would have been present otherwise.



Paced Auditory Serial Addition Test, PASAT, Brain injury, Patterns of Performance, Assessments, Dyad, Skipping