79 The Clinical Utility of Reliable Digit Span in Predicting Effort on the TOMM in Youth with a History of a Concussion
Authors: Steinbaugh Ashlynn , Murley Rachel , Forbes Bradley R , Baldini Daniel , Tupou Talamahe’a A , Flowers Julius , Hirst Rayna B 
Published: December 2023

Objective:Performance validity testing (PVT) is important in neuropsychological evaluations to ensure accurate interpretation of performance. While research shows children pass PVTs with adult cut-offs, PVTs are more commonly used with adults (Lippa, 2018). The Test of Memory Malingering (TOMM), a standalone PVT, is commonly used with adults and children (DeRight & Carone, 2015). The Reliable Digit Span (RDS), an embedded PVT derived from the Digit Span subtest of the Wechsler Intelligence Scales (Wechsler Intelligence Scale for Children-4th Edition, WISC-IV; Wechsler, 2003), is less commonly used with children (DeRight & Carone, 2015). RDS cut-off scores are associated with an increased rate of false positives in children, indicating mixed results regarding the clinical utility in pediatric populations (Welsh et al., 2012). Research shows that youth with a history of concussion (HOC) may demonstrate suboptimal effort for many reasons (e.g., external incentives, boredom, pressure), thus highlighting the need to investigate the utility of PVTs in this population (Araujo et al., 2014; DeRight & Carone, 2015). The present study aimed to examine the clinical utility of RDS in detecting poor effort on the TOMM in youth athletes with a HOC.Participants and Methods:Participants included 174 youth athletes aged 8 to 18 (20.1% female; 42.5% people of color (POC)) who completed a baseline neuropsychological battery that included the TOMM and WISC-IV Digit Span. Of the sample, 29 youth athletes reported a HOC (13.8% female; 37.9 POC). RDS was calculated for each Digit Span administration, and sensitivity (SN) and specificity (SP) were calculated for RDS when invalid performance was operationalized by a more stringent cut-off score of <49 to increase the SN of the TOMM Trial 1 (Stenclik et al., 2013). Receiver operator characteristics (ROC) curve analysis determined whether RDS performance accurately predicted participants’ performance on the TOMM.Results:The ROC curve analysis resulted in an area under the curve (AUC) of just 0.427 for RDS. A cut-off score of <7 (as suggested by Kirkwood et al. (2011)) for RDS results in 100% SN, 8.3% SP, 5% positive predictive validity (PPV), and 95% negative predictive validity (NPV). However, a cut-off score of <9 for RDS results in 75% SN, 15% SP, 25% PPV, and 75% NPV.Conclusions:Little research shows the utility of different PVTs predicting children’s performance on other PVTs, despite evidence that children with a HOC are vulnerable to variable or insufficient effort (Araujo et al., 2014; DeRight & Carone, 2015). In a sample of 29 youth athletes with a HOC, RDS predicted TOMM performance at rates worse than chance. While RDS has advantages as an embedded PVT, its limited ability to predict performance on a standalone PVT suggests interpreting with great caution. These findings highlight the importance of implementing multiple PVTs throughout testing to ensure accurate findings and interpretations, particularly in youth with a HOC. The small sample size is a limitation that possibly impacted the ability of RDS to predict TOMM performance. Further research is needed to understand the utility of RDS as a predictor of PVT performance in different populations. Replication of these findings with a larger sample size is needed to provide confirmatory evidence of poor predictive performance of the RDS.