King-Devick Sensitivity and Specificity to Concussion in Collegiate Athletes

Abstract

Context: The King-Devick (K-D) is used to identify oculomotor impairment following concussion. However, the diagnostic accuracy of the K-D over time has not been evaluated. Objective: (a) Examine the sensitivity and specificity of the K-D test at 0–6 hours of injury, 24–48 hours, asymptomatic, return-to-play, and 6-months following concussion and (b) compare outcomes for differentiating athletes with a concussion from non-concussed across confounding factors (sex, age, contact level, school year, learning disorder, ADHD, concussion history, migraine history, administration mode). Design: Retrospective, cross-sectional design. Setting: Multisite institutions within the Concussion Assessment, Research, and Education (CARE) Consortium. Patients or Other Participants: 1239 total collegiate athletes without a concussion (age=20.31±1.18, male=52.2%) were compared to 320 athletes with a concussion (age=19.80±1.41, male=51.3%). Main Outcome Measure(s): We calculated K-D time difference (sec) by subtracting baseline from the most recent time. Receiver operator characteristics (ROC) and area under the curve (AUC) analyses were used to determine the diagnostic accuracy across timepoints. We identified cutoff scores and corresponding specificity at 80% and 70% sensitivity levels. We repeated ROC with AUC outcomes by confounding factors. Results: King-Devick predicted positive results at 0-6 hours (AUC=0.724, p<0.001), 24-48 hours (AUC=0.701, p<0.001), return-to-play (AUC=0.640, P<0.001), and 6-months (AUC=0.615, P<0.001), but not at asymptomatic (AUC=0.513, P=0.497). The 0–6 and 24–48-hour timepoints yielded an 80% sensitivity cutoff score of −2.6 and −3.2 seconds (faster) respectively, but 46% and 41% specificity. The K-D test had significantly better AUC when administered on an iPad (AUC=0.800, 95%CI:0.747,0.854) compared to the spiral card system (AUC=0.646, 95%CI:0.600,0.692; p<0.001). Conclusions: The K-D test has the greatest diagnostic accuracy at 0–6 and 24–48 hours of concussion, but declines across subsequent post-injury timepoints. AUCs did not significantly differentiate between groups for confounding factors. Our negative cutoff scores indicate that practice effects contribute to improved performance, requiring athletes to outperform their baseline.