HOW PERFORMANCE ON THE PASAT RELATE TO GLOBAL OUTCOME ON THE DISABILITY RATING SCALE FOLLOWING CLOSED-HEAD INJURY.
Wiegand, Lee A.
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Objective: Care, treatment, and rehabilitation of individuals who have sustained a TBI are reliant on our understanding of the factors that predict common outcomes. Cognitive ability, as measured by neuropsychological testing, has proven to be an influential factor in predicting the global outcome of individuals that have sustained a head injury. The PASAT measures processing speed, working memory, and attention, which are cognitive abilities often associated with head injury. This study aimed to elucidate the differences between participants able to complete the PASAT and those who could not. Then the ability of PASAT performance to predict global outcome as measured by the DRS was determined when injury severity were taken into account. Finally, it aimed to determine the ability of PASAT performance to predict outcome when scores of participants unable to complete the PASAT were added to the statistical analysis through imputation. Participants and Method: Data from 169 individuals with complicated mild, moderate, and severe closed head injuries who participated in CPHS approved, NIH funded research that involved the collection of DRS data and neuropsychological testing at six months post injury were used. Groups were created based on an individuals’ ability or inability to complete the PASAT. Demographic, injury severity, and outcome variables were compared. Linear regression models were used to analyze the relationship between PASAT performance and outcome on the DRS at 6 months post injury. These data were analyzed controlling for severity of injury and demographic variables. Imputation methods, including mean substitution, the minimum score substitution, and regression based substitution were used to further assess the relationship between PASAT performance and DRS scores. Results: Ability to complete the PASAT was significantly related to global outcome as measured by the Disability Rating Scale. Performance on the PASAT accounted for 16.4% of the variance in DRS scores when pertinent demographic and injury severity measures were controlled for. Statistical imputation of PASAT data did not increase the amount of variance in DRS scores accounted for by PASAT performance, but 3 of 4 imputation techniques were able to increase the total models’ predictive ability.