There is a need for a reliable and quick method to help screen for concussions in professional soccer. The last 2014 and 2018 FIFA World Cups have demonstrated that concussions during soccer matches pose a challenge for team physicians to diagnose and treat in a timely manner. King Devick (KD) is a rapid sideline screening test used for concussion diagnosis that relies on individual’s baseline measurement.
Purpose: To assess the test re-test reliability of the KD test in a cohort of professional soccer athletes. Methods: 24 professional soccer players from a Mexican First Division Professional Soccer League (Liga MX) team were evaluated. A baseline KD test as well as a SCAT3 Test was conducted before the 2017 season. The tests were repeated 1 year later as a baseline for 2018 season. 10 players transferred to other clubs after the first year were excluded from data analysis. 14 remaining athletes were included in the study. Correlations of year on year KD and SCAT3 measures of individuals were assessed. Statistical analyses were performed with IBM SPSS. Results: Mean KD baseline test time for 2017 (KD1) = 41.71 seconds and for 2018 (KD2) = 41.66 seconds. KD1 and KD2 were strongly and positively correlated (0.93, p value <0.001). 1 player was evaluated for concussion during the season (KD1 = 41.7s, KD after trauma = 44.2s, KD2 = 41.4s). 5 players had slowing of KD2 without having history of concussion during the previous year. 1 player with a self-declared learning disability had significantly slower KD time in follow up test (KD1 = 69.4s, KD2 = 77s). 2017 and 2018 SCAT3 demonstrated positive and significant correlation for balance scores (0.601, p = 0.023), and delayed recall scores (0.596, p = 0.024). Conclusion: Mean KD baseline test results showed a significant correlation between first and second year evaluations. The high correlation suggests that KD testing has adequate reliability for use as a diagnostic test. Of note, 5 players had slower times despite not having a history of concussion during the previous year. It may not be useful when establishing baseline test results in players with learning disabilities due to the considerable variation from KD1 to KD2 in player we evaluated. Further studies need to be done with professional soccer athletes in order to establish quick and efficient methods of diagnosis and management of concussion.