Examining the Incremental Utility of WAIS-IV Letter-Number Sequencing Embedded Performance Validity Tests over Established Digit Span Indices Among Adult ADHD Referrals

Abstract The Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) Digit Span (DS) subtest has been extensively validated as a non-memory-based embedded performance validity test (PVT). This study investigated the incremental utility of multiple indices derived from the Letter-Number Sequence (LNS) subtest over other DS embedded PVTs among 311 adults referred for evaluation of attention-deficit/hyperactivity disorder (ADHD). Results showed DS PVTs were moderately correlated with LNS PVT indices ( r = .35–.67). All DS and LNS PVTs successfully distinguished between valid and invalid performance groups ( np 2 s = .06–.11), and generally showed comparable accuracy for detecting performance invalidity (AUCs = .68–.75) with 8–47% sensitivity/ ≥ 86% specificity. LNS age-corrected scaled score and longest LNS had the highest sensitivities (45–47%). When examined together, established DS PVTs were the more robust predictor of validity status. LNS PVTs showed some incremental utility, but the resulting increase in classification accuracy was comparatively modest, indicating a degree of redundancy if used in combination with DS PVTs.