Reasons for Study

Sideline assessment tools are an important component of concussion evaluations. To date there has been little data evaluating the clinical utility of these tests in professional football. The purpose of this study was to evaluate the clinical utility of the King-Devick (K-D) Test in evaluating concussions in professional football players. Baseline data was collected over 2 consecutive seasons in the Canadian Football League as part of a comprehensive medical baseline evaluation. A pilot study with the K-D began in 2015 with 306 participants and the next year (2016) there were 917 participants. In addition, a sample of 64 participants completed testing after physical exertion (practice or game).

Main Findings

Participants with concussion demonstrated significantly higher (slower) results compared with baseline and the exercise group (F[2,211] = 5.94, p = 0.003). The data revealed a specificity of 84% and sensitivity of 62% for our sample. Reliability from season to season was good (ICC2,1 = 0.88, 95% CI: 0.83, 0.91). On average participants improved performances by a mean of 1.9 seconds (range -26.6 to 23.8) in subsequent years. High reliability was attained in the exercise group. (ICC2,1 = 0.93, 95% CI: 0.89, 0.96).


The K-D test presents as a reliable measure although sensitivity and specificity data from our sample indicate it should be used in conjunction with other measures for diagnosing concussion. Further research is required to identify stability of results over multiple usages.

Summary Points:

  • The K-D test identified a mean change in K-D Test scores of 5.1 seconds between post-injury and baseline measures.
  • The data showed a 62% sensitivity and 84% specificity with a positive predictive value of 84% and negative predictive value of 62%.
  • Reliability analysis showed strong reliability from season to season and within the exercise group.
  • The K-D Test provides helpful clinical data for concussion diagnosis although it is not recommended for use as a standā€alone test.
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