Objective: To evaluate the between trial reliability of the King-Devick (KD) test.
Background: The KD test is a reading efficiency test meant to provide an assessment of cognitive visual processing. Administration of the test requires two trials; however the reliability of trial one to trial two is unknown.
Design/Methods: 3193 KD test scores were evaluated from 2,373 NCAA athletes (1,110 female, 1,263 male, 20.22±2.32 years old, 70.28±4.51 inches,177.72 ±76.36 lbs.) from five institutions that underwent baseline KD testing over a two-year period as part of the NCAA/DoD CARE protocol. All testing was completed prior to their athletic season. Subjects were instructed to read aloud numbers from three cards as quickly as possible without making errors. The cumulative time from all three cards was the score for that trial with two trials being conducted. The outcome measures were the times for trial one and trial two. A Pearson correlation and reliable change index (RCI) were calculated.
Results: There was a significant positive correlation between trial one (43.05±7.97 seconds, range 23.84 – 103.8 seconds) and trial two (40.7 sec ± 7.46, range 22.38 – 86.55 seconds) with an r of 0.882, p<0.001. A majority of subjects improved on the second trial (n=2452, 77%) with 25 subjects receiving the same score and 716 (22%) scoring worse on the second trial. The mean improvement was 2.35 seconds with a median of 2.2 seconds. The RCI was calculated at 7.59 seconds with 219 (7%) of the subjects exceeding the RCI.
Conclusions: The results of the study suggest that the KD test is stable across both trials at baseline. However, a modest learning effect of approximately 2.3 seconds should be expected on the second trial suggesting the second trial is necessary for an accurate baseline score.
Summary Points:
- K-D Test is stable across both trials at baseline with a modest learning effect of approximately 2.3 seconds should be expected on the second trial suggesting that the second trial is necessary for an accurate baseline score.