Objective: Concussion, defined as an impulse blow to the head or body resulting in transient neurologic signs or symptoms, has received increasing attention in sports at all levels. The King-Devick (K-D) test is based on the time to perform rapid number naming and captures eye movements and other correlates of suboptimal brain function. In a study of boxers and mixed martial arts (MMA) fighters, the K-D test was shown to have high degrees of test-retest and inter-rater reliability and to be an accurate method for rapidly identifying boxers and mixed martial arts fighters with concussion. We performed a study of the K-D test as a rapid sideline screening tool in collegiate athletes to determine the effect of concussion on K-D scores compared to a pre-season baseline.
Methods: In this longitudinal study, athletes from the University of Pennsylvania varsity football, sprint football, and women’s and men’s soccer and basketball teams underwent baseline K-D testing prior to the start of the 2010-11 playing season. Post-season testing was also performed. For athletes who had concussions during the season, K-D testing was administered immediately on the sidelines and changes in score from baseline were determined.
Results: Among 219 athletes tested at baseline, post-season K-D scores were lower (better) than the best pre-season scores (35.1 vs. 37.9s, P=0.03, Wilcoxon signed-rank test), reflecting mild learning effects in the absence of concussion. For the 10 athletes who had concussions, K-D testing on the sidelines showed significant worsening from baseline (46.9 vs. 37.0s, P=0.009), with all except one athlete demonstrating worsening from baseline (median 5.9s).
Conclusion: This study of collegiate athletes provides initial evidence in support of the K-D test as a strong candidate rapid sideline visual screening tool for concussion. Data show worsening of scores following concussion, and ongoing follow-up in this study with additional concussion events and different athlete populations will further examine the effectiveness of the K-D test.
Summary Points:
- 219 collegiate football, female and male soccer and basketball players performed the K-D Test pre-season and post-season. Athletes who suffered a concussion were tested immediately following trauma.
- Non-concussed athletes’ post-season scores minimally improved from baseline due to a learning effect.
- 10 players sustained concussions and had significantly worse scores on the K-D Test from baseline with a median change of 5.9 seconds slower.
In a fatigue trial, the men’s basketball team was tested immediately after a scrimmage. They showed improved scores from baseline, demonstrating that the post-workout fatigue does not worsen K-D scores.