Using a novel Reliable Letter-Number Span from the Wechsler Letter-Number Sequencing as an embedded validity indicator in baseline concussion testing for youth athletes.

Objective: Few performance validity tests exist for youth undergoing baseline testing for the management of sport-related concussion. This study provides an initial validation of a reliable span calculation from the Wechsler Intelligence Scale for Children-Fourth Edition Letter-Number Sequencing (LNS) subtest as a performance validity indicator for youth baseline testing (Reliable Letter-Number Span; RLNS). Method: Youth athletes (n = 173) underwent baseline concussion testing for the management of sport-related concussion. We classified participants as valid (n = 153) or invalid performance (n = 20) based on several well-established performance validity tests. We calculated RLNS by summing the spans of alphanumeric characters across two items within the Letter-Number Sequencing subtest, similar to the Reliable Digit Span. To better determine the utility of RLNS, we also examined other novel reliable span metrics and established summary scores from the Letter-Number Sequencing as potential validity indicators. Results: Analyses revealed excellent classification accuracy for RLNS, with an area under the curve of .88 (95% CI [.81, .96]). The optimal cutoff for RLNS (≤6) yielded .55 sensitivity and .95 specificity. Results showed similar but slightly lower classification accuracy statistics (areas under the curve of .77-.86) for the other LNS validity indicators. Conclusion: Initial findings support the criterion validity of RLNS as an embedded validity indicator. This measure is among the few extant performance validity tests that may be appropriate for youth baseline concussion testing. RLNS may also be appropriate for other types of pediatric evaluations. However, additional support is necessary before neuropsychologists can use RLNS clinically.