Reliable change on ImPACT version 2.0 following sport concussion

Archives of Clinical Neuropsychology. 2003 Oct;


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



Objective: To examine the stability and to calculate the reliable change confidence intervals for the test–retest difference scores for Version 2.0 of ImPACT (Immediate Post-Concussion Assessment and Cognitive Testing). Method: Forty-six non-concussed adolescents and young adults completed the test battery twice. Test–retest coefficients, reliable change difference scores, and confidence intervals for measurement error are provided. These reliable change parameters were applied to 41 concussed amateur athletes who were tested preseason and within 72 h of injury. Results: In the healthy sample, the test–retest coefficients for the composite scores ranged from 0.56 to 0.84. The 80% confidence intervals for estimating change were: Verbal Memory = 10 points, Visual Memory = 14 points, Reaction Time = 0.06 s, Processing Speed = 5 points, and Post-concussion Total Scores = 10 points. From preseason to post-concussion, the concussed athletes demonstrated a decline in Verbal Memory(P<.0002,d=0.82) and Visual Memory (P<.0002,d=0.69); slower Processing Speed (P<.006,d=0.49), and Reaction Time (P<.00005,d=0.95); and a large increase in symptom reporting(P<.00001,d=0.99). Across the composites, the percentage of athletes who showed significant negative change ranged from 39 to 54%. Concussed athletes were much more likely to have two or more declines across the composites than the healthy subjects (63.4% vs. 6.5%;P<.00001; OR=24.8, 95%CI=6.6–94.1). Conclusion: Applying these confidence intervals allows more precise determinations of deterioration, improvement, and recovery in the initial days following concussion

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