The King-Devick (K-D) test is often used as part of a multimodal assessment to screen for sport-related concussion. However, the test involves reading numbers, and little is known about variation in baseline performance on the K-D by reading skill level. We conducted a cross-sectional study analyzing data from the Concussion Assessment, Research and Education (CARE) Consortium to assess differences in baseline performance on the K-D associated with factors that impact reading skill level (learning disorder [LD] and primary home language other than English [PHLOTE]), while controlling for covariates (gender, type of sport, attentional issues, history of concussion and modality of administration). We had a sample of 2311 student-athletes (47% female), and multivariate regression indicated an average K-D performance time of 40.4 s. Presence of LD was associated with a 3.3 s slower K-D time (95% CI 1.9-4.7, p < 0.001), and PHLOTE was associated with a 2.6 s slower K-D time (95% CI 1.2-4.0, p < 0.001), after controlling for other covariates. These results suggest caution in the use of normative data with the K-D. Future studies should explore the impact of factors associated with reading skill level on sensitivity of the K-D in detecting concussion.
Keywords: Concussion; Learning disorder; Mild traumatic brain injury; Oculomotor; Saccades; Screening; Sport.