Long-term test-retest evaluation of the King-Devick test in youth soccer athletes

Despite the clinical utility of baseline comparisons during concussion assessments, little evidence exists on long-term test-retest reliability of baseline tests in youth athletes. In addition, sex differences in baseline performance are inconsistent in youth athletes, warranting further research. The purpose was to examine sex differences, prevalence of false-positive scores, and long-term test-retest reliability of the King-Devick (KD) test. Healthy youth athletes (23 males, 28 females) completed the KD test prior to the Spring 2016 and Fall 2017 seasons. Two-way random-effects intraclass correlation coefficients (ICCs) were utilized to determine test-retest reliability. A mixed between-within ANOVA with post-hoc t-tests were used to identify the interaction between sex and season, and frequencies were used to determine abnormal test score prevalence. The KD test demonstrated good test-retest reliability (0.77[95% CI, 0.43-0.89]), with 11.8% of youth athletes having clinically meaningful improvements between Season 1 to Season 2. There was a significant sex*season interaction (F_(1,49) = 4.67, p = .04), with significantly greater improvements between seasons in male youth athletes compared to female youth athletes. However, 33-35% of youth athletes displayed abnormal test scores in Season 2 relative to Season 1. The KD test demonstrated good reliability and only a small percentage had clinically meaningful changes, however a high prevalence of false-positive scores were observed in this sample.