Tracking recovery from concussion using ImPACT: applying reliable change methodology

Archives of Clinical Neuropsychology -


Iverson, G. L., M. R. Lovell, M. W. Collins and J. Norwig.



Return to play following concussion is one of the most challenging decisions facing coaches, athletic trainers, and sports medicine physicians. The purpose of this study was to examine the psychometric characteristics of Immediate Postconcussion Assessment and Cognitive Testing (ImPACT), a computerized neuropsychological test battery designed to assess recovery from sports-related concussion. The focus was on the stability of the test scores and the calculation of reliable change confidence intervals for the test–retest difference scores. Participants were 49 amateur athletes who completed the computerized test battery at least twice, with an average retest interval of 14 days (range = 7–21). Their average age was 17.8 years (S.D. = 2.6, range = 14–23). The male–female gender ratio was 78:22. Fifty-four percent were high school athletes and 46% played college-level sport. There were no statistically significant practice effects for the three ImPACT composite scores. Standard error of measurements for Times 1 and 2 were calculated, and from these the standard error of difference was computed for the three composite scores. The 0.80 confidence interval for reliable change was 10 points for the memory composite, 0.10 s for the reaction time composite, and 8 points for the processing speed composite. Applying these confidence intervals allows more precise determinations of deterioration, improvement, and recovery in the initial days following concussion. Three case examples of concussed high school athletes are presented to illustrate the clinical application of this methodology

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