Reliability and Minimal Detectable Change of the Standardized Assessment of Reaction Time

Abstract

Context: Postconcussion reaction time deficits are common, but existing assessments lack sport-related applicability. We developed the Standardized Assessment of Reaction Time (StART) tool to emulate the simultaneous cognitive and motor function demands in sport, but its reliability is unestablished. Objectives: To determine the intrarater, interrater, and test-retest reliability of StART and to examine the dual-task effect, time effect, and relationships between StART and computerized and laboratory-based functional reaction time assessments. Design: Prospective cohort study. Setting: Clinical laboratory. Patients or Other Participants: Twenty healthy, physically active individuals (age = 20.3 6 1.8 years, females = 12, no concussion history = 75%). Main Outcome Measure(s): Participants completed the StART, computerized reaction time (Stroop task via CNS Vital Signs), and laboratory-based jump landing and cutting reaction time under single-task and dual-task (subtracting by 6s or 7s) cognitive conditions at 2 testing sessions a median of 7 days apart. We used intraclass correlation coefficients (ICCs), repeated-measure analysis of variance, and Pearson r correlations to address our aims. Results: Overall, good to strong interrater (ICC [2,k] range = 0.83—0.97), intrarater (ICC [3,k] range = 0.91—0.98), and test-retest (ICC [3,k] range = 0.69—0.89) reliability were observed. A significant reaction time assessment-by-cognitive condition interaction was present (P = .018, ηp2 = 0.14), with StART having the largest dual-task effect. Main time effects for dual-task conditions were seen across all reaction time assessments (mean difference = -25 milliseconds, P = .026, ηp2 = 0.08) with improved performance at the second testing session. No StART outcomes correlated with computerized reaction time (P . .05), although some correlated with single-task (r range = 0.42—0.65) and dual-task (r range = 0.19—0.50) laboratory cutting reaction time. Conclusions: The StART demonstrated overall reliable performance relative to other reaction time measures. Reliability coupled with a strong dual-task effect indicates that StART is a valid measure for examining functional reaction time and may have future utility for sport-related concussion return-to-play decision-making.