ImPact test-retest reliability: reliably unreliable?

J Athl Train. 2013 Jul-Aug;48(4):506-11. doi: 10.4085/1062-6050-48.3.09. Epub 2013 May 31.


Context: Computerized neuropsychological testing is commonly used in the assessment and management of sport-related concussion. Even though computerized testing is widespread, psychometric evidence for test-retest reliability is somewhat limited. Additional evidence for test-retest reliability is needed to optimize clinical decision making after concussion.

Objective: To document test-retest reliability for a commercially available computerized neuropsychological test battery (ImPACT) using 2 different clinically relevant time intervals.

Design: Cross-sectional study.

Setting: Two research laboratories.

Patients or other participants: Group 1 (n = 46) consisted of 25 men and 21 women (age = 22.4 ± 1.89 years). Group 2 (n = 45) consisted of 17 men and 28 women (age = 20.9 ± 1.72 years).

Intervention(s): Both groups completed ImPACT forms 1, 2, and 3, which were delivered sequentially either at 1-week intervals (group 1) or at baseline, day 45, and day 50 (group 2). Group 2 also completed the Green Word Memory Test (WMT) as a measure of effort.

Main outcome measures: Intraclass correlation coefficients (ICCs) were calculated for the composite scores of ImPACT between time points. Repeated-measures analysis of variance was used to evaluate changes in ImPACT and WMT results over time.

Results: The ICC values for group 1 ranged from 0.26 to 0.88 for the 4 ImPACT composite scores. The ICC values for group 2 ranged from 0.37 to 0.76. In group 1, ImPACT classified 37.0% and 46.0% of healthy participants as impaired at time points 2 and 3, respectively. In group 2, ImPACT classified 22.2% and 28.9% of healthy participants as impaired at time points 2 and 3, respectively.

Conclusions: We found variable test-retest reliability for ImPACT metrics. Visual motor speed and reaction time demonstrated greater reliability than verbal and visual memory. Our current data support a multifaceted approach to concussion assessment using clinical examinations, symptom reports, cognitive testing, and balance assessment.

MeSH terms

  • Adult
  • Analysis of Variance
  • Brain Concussion / diagnosis
  • Cognition Disorders / diagnosis
  • Cross-Sectional Studies
  • Diagnosis, Computer-Assisted
  • Female
  • Humans
  • Male
  • Neuropsychological Tests / standards*
  • Psychometrics
  • Reproducibility of Results
  • Young Adult