King-Devick testing and concussion recovery time in collegiate athletes

Abstract

Objectives: To assess whether the King-Devick (KD) test is useful as a prognostic test for prolonged concussion symptoms by examining the relationship between a) change in performance on KD test from baseline to within two days post-injury and b) the absolute KD time at post-concussion testing, with an outcome of time to return to play (RTP). Design: Prospective Cohort Study. Methods: Collegiate varsity athletes in the Concussion Assessment, Research, and Education (CARE) Consortium completed baseline and post-injury King-Devick tests from 2014 to 2018. Two exposures were evaluated: 1) change in KD score from baseline to within two days post-injury and 2) absolute KD score within two days post-injury, adjusted for baseline KD. We used Cox proportional hazards models to analyze the relationships between these exposures and time to RTP post-concussion. Results: A total of 309 concussion injuries were included. Median baseline KD score was 40.0 s (IQR: 35.8, 45.2). Median post-injury KD score was 45.8 s (IQR: 39.8, 57.1). Median number of days until RTP in this cohort was 11 (IQR: 8, 17). Post-injury KD score adjusted for baseline KD had a stronger association with time to RTP duration (HR: 0.99 (0.98, 1.00), p = 0.03) than the difference in KD score from baseline to post-injury (HR: 0.99 (0.99, 1.00), p = 0.07). Conclusions: Higher post-injury KD scores are associated with longer RTP. The association between KD post-concussion test and longer RTP warrants further investigation to assess the utility of the KD for prognostication in a clinical setting.