Profile analysis as a new methodology for interpreting neurocognitive test scores following concussion

British Journal of Sports Medicine. 2009 May;

43(Suppl 1):i100.

Iverson, G. L. and B. L. Brooks.

Abstract:

Objective: To develop a new method, with known false positive rates, for interpreting neurocognitive test performance in concussed high school athletes. This method, called neuropsychological profile analysis, allows the clinician or researcher to interpret multiple test scores simultaneously. Design: An archival normative database was used to conceptualise the profile analyses criteria with fixed and known false positive rates. These criteria were then applied to a sample of acutely concussed high school football players. Setting: Injured subjects were recruited from high schools in Pennsylvania. Subjects: Healthy adolescent boys (N = 341), aged 13–18 years, completed computerised neurocognitive testing. These subjects comprise the normative data for ImPACT. A sample of 125 high school football players completed testing within 5 days of sustaining a concussion. Outcome Measures: ImPACT is a brief computer-administered neurocognitive test battery that consists of six individual test modules that measure attention, memory, reaction time and processing speed. The four primary composite scores used in this study were verbal memory, visual memory, reaction time and processing speed. The prevalence rates of low scores in the normative sample and concussed sample were computed based on different cut-off scores (ie, 25th, 16th, 10th, 5th and 2nd percentile ranks). Results: Criteria for cognitive impairment, based on the prevalence of low test scores, were established with false positive rates from 4% to 8%. The percentage of concussed athletes who had an unusual number of low scores was as follows: one or more scores at or below the 2nd percentile 52.0%; two or more scores below the 10th percentile 44.0%; three or more scores below the 16th percentile 39.2% and four or more scores below the 25th percentile 20.0%. Conclusions: This new method for interpreting multiple neurocognitive test scores simultaneously has a known false positive rate and increases the clinical accuracy for identifying frank cognitive impairment associated with sport-related concussion.

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