Factor Analysis of the ImPACT Subtests: An Examination of ImPACT Composite Scores

J Int Neuropsychol Soc. 2011 Mar;

17(s1):329.

Rabinowitz, A. and P. Arnett.

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Abstract:

Objective: The Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) battery is a popular tool for the diagnosis and management of sports-related concussion. The ImPACT clinical report provides five composite scores, to aid in test interpretation: Verbal Memory, Visual Memory, Visual Motor Speed, Reaction Time, and Impulse Control. The present study sought to validate this purported factor structure in an independent sample. Participants and Methods: Five-hundred and fifty-five non-injured college athletes were administered the ImPACT at baseline. A structural equation modeling (SEM) approach to exploratory factor analysis (EFA) was conducted to determine the underlying factor structure of the ImPACT tests. Then, using the results from the EFA, a confirmatory SEM model was created in order to obtain factor loadings and interpret the factors. All analyses were done using LISREL 8.8 (Joreskog and Sorbom, 2006). Results: A four factor EFA model yielded excellent fit to the data (χ226=37.2, p=.07; SRM=.02; CFI=.99). The four factors were then subject to an oblique rotation. The resulting pattern matrix was fit to a confirmatory model, which yielded an acceptable fit to the data (χ247=113.65, p<.01; SRM=.06; CFI=.96). Examination of the final solution suggested that the four retained factors measure: Memory, Attention, Impulsivity, and Speeded Processing. Conclusions: These findings suggest that the ImPACT tests have a four factor structure. The factors purported by the authors of the ImPACT were not supported by the present analyses. Importantly, verbal and visual memory tasks loaded on the same factor, and reaction time measures loaded on different factors (Attention, Impulsivity, or Speeded Processing). Clinical implications will be discussed.

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