Utility of the SCQ and RBS-R to Confirm Caseness of Adolescents and Adults in ASD Research

Friday, May 13, 2016: 5:30 PM-7:00 PM
Hall A (Baltimore Convention Center)
L. A. Pepa1 and V. Hus Bal2, (1)Center for Autism and the Developing Brain, Weill Cornell Medicine, White Plains, NY, (2)Department of Psychiatry, University of California San Francisco, San Francisco, CA
Background: Better tools are needed to screen and diagnose adolescents and adults with ASD (IACC, 2013). The Autism Diagnostic Interview-Revised (ADI-R; Rutter et al., 2003a) may be useful to establish “caseness,” but is cost and time-intensive and often infeasible for parents of older individuals. Less is known about the predictive validity of the Social Communication Questionnaire Lifetime and Current forms (SCQ-L, SCQ-C; Rutter et al., 2003b) in older samples. The original SCQ validation (Berument et al., 1999) included individuals from 4-40 years, but did not report findings separately by age group. In a study of adults with ID, both SCQs yielded good sensitivity (79-89%), but low specificity (SCQ-C=66%; SCQ-L=48%; Sappok et al., 2015). No study has examined the predictive validity of the SCQ in adolescent or adult ASD samples spanning the full range of cognitive ability.

Objectives: This study aims to 1) compare sensitivity and specificity of the SCQ-L, SCQ-C and ADI-R and 2) assess whether combination with the Repetitive Behavior Scale-Revised (RBS-R; Bodfish et al., 2000) improves predictive validity.

Methods: Participants were drawn from a study focused on improving ASD diagnostic methods for adolescents and adults. Analyses included 49 individuals with diagnoses of ASD and 12 participants with non-ASD diagnoses (Age M=19.70, SD=3.43; NVIQ M=79.54, SD=32.57) who had an ADI-R, SCQ-C, SCQ-L and RBS-R completed at a single time point. ADI-R sensitivity and specificity were based on standard algorithm cutoffs and CPEA criteria (Lainhart et al., 2006); for both SCQ forms, cutoff=15. ROC analyses were used to derive cutoffs for SCQ-C, SCQ-L and RBS-R.

Results: For both groups, the SCQ showed moderate to strong correlations with the ADI-R and IQ. The ADI-R yielded the best balance of sensitivity (78-88%) and specificity (67-71%) using standard or CPEA criteria, respectively. The SCQ-L offered comparable sensitivity (76%), but poorer specificity (58%); a cutoff of 16 yielded somewhat better specificity (67%) without significant reduction in sensitivity (73%). In contrast, the SCQ-C yielded superior specificity (92%), but poor sensitivity (47%); lowering the cutoff to 13 reduced specificity (67%) and only improved sensitivity to 61%. Combining SCQ-L and SCQ-C did not improve predictive validity over either form alone. Although not intended as a screener, an RBS-R cut-off of 10 yielded results comparable to the SCQ-L (sensitivity=71%, specificity=58%). Requiring participants to meet on the SCQ-L or RBS-R provided the same balance of sensitivity (78%) and specificity (67%) as the standard ADI-R. Combining the SCQ-C and/or the RBS-R resulted in good specificity (>83%), but sensitivity remained below 62%.

Conclusions: Combining the SCQ-L and RBS-R yielded comparable sensitivity and specificity to the ADI-R, suggesting this combination may be a useful alternative to confirm “caseness” in adolescent and adult ASD research. In a sample of more diverse cognitive abilities, SCQ-C provided higher specificity, but lower sensitivity than studies of individuals with ID (Sappok et al., 2015); similar results with the SCQ-L were achieved, albeit with a lower cutoff. Future directions include replicating results in an independent sample and exploring whether combination with the ADOS further improves predictive validity.