King-Devick Test Time Varies by Testing Modality.

OBJECTIVE: To explore differences in baseline King-Devick Test (KD) completion time between 2 testing modalities: (1) spiral-bound paper cards (cards) and (2) iPad application (iPad). DESIGN: Cross-sectional cohort analysis. SETTING: National Collegiate Athlete Association (NCAA) institutions. PARTICIPANTS: Student athletes from 13 women's and 11 men's collegiate sports who completed KD baseline testing as part of their first year in the Concussion Assessment, Research and Education (CARE) Consortium from 2014 to 2016 (n = 2003, 52.2% male). INDEPENDENT VARIABLES: King-Devick Test modalities; cards or iPad. MAIN OUTCOME MEASURE: Baseline KD completion time (seconds). RESULTS: Mean baseline KD completion time of the iPad modality group [42.8 seconds, 95% confidence interval (CI), 42.1-43.3] was 2.8 seconds (95% CI, 2.1-3.4) greater than the cards group (40.0 seconds, 95% CI, 39.7-40.3) (t(1, 1010.7) = -8.0, P < 0.001, Cohen's d = 0.41). CONCLUSIONS: Baseline KD performance is slower when tested on an iPad than when tested on spiral-bound paper cards. The 2 KD modalities should not be used interchangeably in concussion assessments because differences in the modalities can lead to time differences similar in magnitude to those used to indicate concussion. From a research perspective, modality may influence interpretation and/or synthesis of findings across studies.

Relationship Between the King-Devick Test and Commonly Used Concussion Tests at Baseline.

CONTEXT: Comprehensive assessments are recommended to evaluate sport-related concussion (SRC). The degree to which the King-Devick (KD) test adds novel information to an SRC evaluation is unknown. OBJECTIVE: To describe relationships at baseline among the KD and other SRC assessments and explore whether the KD provides unique information to a multimodal baseline concussion assessment. DESIGN: Cross-sectional study. SETTING: Five National Collegiate Athletic Association institutions participating in the Concussion Assessment, Research and Education (CARE) Consortium. PATIENTS OR OTHER PARTICIPANTS: National Collegiate Athletic Association student-athletes (N = 2258, age = 20 ± 1.5 years, 53.0% male, 68.9% white) in 11 men's and 13 women's sports. MAIN OUTCOME MEASURE(S): Participants completed baseline assessments on the KD and (1) the Symptom Inventory of the Sport Concussion Assessment Tool-3rd edition, (2) the Brief Symptom Inventory-18, (3) the Balance Error Scoring System, (4) the Standardized Assessment of Concussion (SAC), (5) the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test battery, and (6) the Vestibular/Ocular Motor Screening tool during their first year in CARE. Correlation coefficients between the KD and the 6 other concussion assessments in isolation were determined. Assessments with ρ magnitude >0.1 were included in a multivariate linear regression analysis to evaluate their relative association with the KD. RESULTS: Scores for SAC concentration, ImPACT visual motor speed, and ImPACT reaction time were correlated with the KD (ρ = -0.216, -0.276, and 0.164, respectively) and were thus included in the regression model, which explained 16.8% of the variance in baseline KD time (P < .001, Cohen f2 = 0.20). Better SAC concentration score (ß = -.174, P < .001), ImPACT visual motor speed (ß = -.205, P < .001), and ImPACT reaction time (ß = .056, P = .020) were associated with faster baseline KD performance, but the effect sizes were small. CONCLUSIONS: Better performance on cognitive measures involving concentration, visual motor speed, and reaction time was weakly associated with better baseline KD performance. Symptoms, psychological distress, balance, and vestibular-oculomotor provocation were unrelated to KD performance at baseline. The findings indicate limited overlap at baseline among the CARE SRC assessments and the KD.

Concussion BASICS II: Baseline serum biomarkers, head impact exposure, and clinical measures.

OBJECTIVE: To examine the effect of concussion history and cumulative exposure to collision sports on baseline serum biomarker concentrations, as well as associations between biomarker concentrations and clinical assessments. METHODS: In this observational cohort study, ß-amyloid peptide 42 (Aß42), total tau, S100 calcium binding protein B (S100B), ubiquitin carboxy-terminal hydrolyzing enzyme L1 (UCH-L1), glial fibrillary acidic protein, microtubule associated protein 2, and 2',3'-cyclic-nucleotide 3'-phosphodiesterase serum concentrations were measured in 415 (61% male, 40% white, aged 19.0 ± 1.2 years) nonconcussed collegiate athletes without recent exposure to head impacts. Regression analyses were used to evaluate the relationship between self-reported history of concussion(s), cumulative years playing collision sports, clinical assessments, and baseline biomarker concentrations. Football-specific analyses were performed using a modified Cumulative Head Impact Index. Clinical assessments included symptom, cognitive, balance, and oculomotor tests. RESULTS: Athletes with a greater number of concussions had a higher baseline Aß42 concentration only (ρ = 0.140, p = 0.005, small effect size). No biomarker concentrations correlated with cumulative exposure to collision sports. Race status fully mediated the correlations of S100B, UCH-L1, and Aß42 with cognitive scores. Football exposure, specifically, was not associated with serum biomarker concentrations or clinical assessment scores based on the modified Cumulative Head Impact Index. CONCLUSION: Concussion-related serum biomarkers showed no consistent association with concussion history, cumulative exposure to collision sports, or clinical assessments in a sample of healthy collegiate athletes. Serum Aß42 concentrations could increase following multiple previous concussions. Considering race status is essential when investigating links between biomarkers and cognition. The biomarkers studied may not detect residual effects of concussion or repetitive head impact exposure in otherwise asymptomatic collegiate athletes without recent exposure to head impacts. Much more research is needed for identifying reliable and valid blood biomarkers of brain trauma history.

Concussion BASICS III: Serum biomarker changes following sport-related concussion.

OBJECTIVE: To evaluate changes in serum biomarker concentrations (ß-amyloid peptide 42 [Aß42], total tau, ubiquitin carboxy-terminal hydrolyzing enzyme L1, S100 calcium binding protein B [S100B], glial fibrillary acidic protein [GFAP], microtubule associated protein 2 [MAP2], and 2',3'-cyclic-nucleotide 3'-phosphodiesterase [CNPase]) after sport-related concussion (SRC) in a sample of collegiate athletes. Associations with clinical outcomes were also investigated. METHODS: Participants in this case-control study included 36 athletes (50% male, 61% white, aged 19.7 ± 1.0 years) with SRC. Twenty-nine also had baseline blood drawn, allowing for within-patient analyses of concentration changes. Between-group analyses incorporated 86 demographically matched controls (51% male, 63% white, aged 19.6 ± 1.1 years). Biomarker sensitivity/specificity for SRC vs controls and relative to standardized normative cutoffs was evaluated (receiver operating characteristics). We also analyzed associations between post-SRC clinical outcomes and both biomarker change from baseline and post-SRC concentrations. RESULTS: The majority of blood samples had concentrations of GFAP, MAP2, and CNPase below limits of quantification. Within-patient analyses indicated elevated S100B after SRC (p = 0.003, 67% of patients elevated), especially for blood samples collected <4 hours post-SRC (88% of patients). Significant between-group differences were limited to blood draws <4 hours post-SRC: Aß42 (81% of SRC > control median, area under the curve [AUC] = 0.75 [95% confidence interval 0.59-0.91]), total tau (75% SRC > control, AUC = 0.74 [0.56-0.79]), and S100B (88% SRC > control; AUC [specific to white race] = 0.82 [0.72-0.93]). Using standardized normative cutoffs (z > 1.0), specificity ranged from 79.1% to 89.3% while sensitivity was <70%. Biomarkers were not associated with clinical outcomes. CONCLUSION: For SRC, diagnostic accuracy of serum biomarkers appears best if blood is collected within a few hours. Accurate blood marker identification of SRC appears somewhat dependent on the "healthy" comparison. Additional research must evaluate whether physiologic changes in the absence of clinical changes, or vice versa, are relevant for concurrent or future neurologic health. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that certain serum biomarkers are elevated from baseline and higher than demographically matched controls after sport-related concussion.