Background: Concussion is a common injury reported in high velocity or contact sport, and a large amount of controversy regarding set protocols for proper management still remains. However, neuropsychological testing, done in accordance with the baseline method, is widely accepted as one of the safest management methods of a concussion. The baseline compared with post-injury testing protocol improves the neuropsychological test�s ability to quantify cognitive decline.
However, the period that the baseline remains valid is unknown, and it is suggested that it should be re-assessed periodically to accommodate natural growth and development of the brain, especially in children and adolescents.
Aim: To determine the test-retest reliability of baseline values for two consecutive years for both the King-Devick and the Cogstate tests.
Methods: A prospective study design, conducted over a two year period, where each athlete acted as his/her own control was used. The test scores and the difference between baseline scores were recorded as the quantitative data for this study.
The study sample consisted out of high school, male and female, students (age 13 to 18) that participated in any school-related sport. Parental consent and participant assent were obtained prior to the sporting season.
This study included the baseline values of the King-Devick test and the computer-based Cogstate sports test.
King-Devick test: There is a statistically significant difference (p = 0.004) between 2016 and 2017 baseline values with a low to medium effect size (Cohen�s D: 0.38). Test-retest reliability was found to be low (0.54) between 2016 and 2017 baseline values, and unfit for clinical standards.
Cogstate sport test: A statistically significant difference was observed for task one (psychomotor task) (p = 0.003) and task two (visual attention task) (p = 0.005). No statistically significant difference was seen for task three (visual learning) (p = 0.703) and task four (working memory) (p = 0.149). All effect sizes were low to poor (Cohen�s D: - 0.324 to -0.044). Low test-retest reliability (0.58 to 0.17) was found for each task between 2016 and 2017 baseline values.
Conclusion: The findings of this study indicate that a new baseline should be conducted pre-season for each sporting season. This is to control for the test-retest reliability scores that decline with time, and for the changes in cognitive performance accompanied with maturation.
King-Devick test: The two main factors are sex age of the participant, more prominent under younger ages.
Cogstate sport test: Sex does not seem to be a factor, only age, more prominent in the younger ages.