Psychometric Study of the Social Responsiveness Scale in Phelan–McDermid Syndrome

Abstract

The Social Responsiveness Scale‐2 (SRS‐2) is a quantitative measure used to characterize symptoms of autism spectrum disorder (ASD). However, research suggests that SRS‐2 scores are significantly influenced by language ability and intellectual disability (ID). Efforts to refine the SRS‐2 by Sturm, Kuhfeld, Kasari, and Mccracken [Journal of Child Psychology and Psychiatry, 58(9), 1053–1061] yielded a shortened form, yet its psychometric properties in populations with severe ID remain unknown. This study aims to examine the psychometric properties of the SRS‐2 in Phelan–McDermid syndrome (PMS), a genetic condition associated with ASD and ID, thereby guiding score interpretation in this population and future development of targeted scales. Analyses, including Item Response Theory (IRT), were conducted on a sample of individuals with PMS (n = 91) recruited at six sites nationally. Psychometric properties evaluated include measures of reliability (internal consistency, test–retest reliability) and validity (structural, construct, content). While both SRS‐2 forms are reliable, the shortened SRS‐2 shows superior validity to the full SRS‐2 for measuring ASD symptoms in PMS. On IRT analysis, the shortened SRS‐2 shows excellent discrimination and precisely evaluates respondents across a wide range of ASD symptomatology but interpretation is limited by uncertain content validity and small sample size. The shortened SRS‐2 shows some promise for use in PMS, but future refinements and additions are needed to develop items that are tailored to identify ASD in children with severe ID and specifically PMS. Lay Summary This study determined that a shortened form of the Social Responsiveness Scale, Second Edition (SRS‐2) shows both promise and limitations for the characterization of autism symptomatology in individuals with Phelan–McDermid syndrome (PMS), a population characterized by intellectual disability (ID). Caution should be used when interpreting SRS‐2 scores in individuals with ID and future research should modify existing items and develop new items to improve the SRS‐2's ability to accurately characterize autism symptomatology in PMS. Autism Res 2020, 13: 1383–1396. © 2020 International Society for Autism Research, Wiley Periodicals, Inc.

Parent-reported measure of repetitive behavior in Phelan-McDermid syndrome

“…Finally, in our neurodevelopmental phenotyping, we did not analyze data from ADOS-2 or ADI-R, given that a majority of our cohort had severe-profound ID and a mental age < 18 months, below the threshold for which these measures are valid. In fact, a recent analysis of data collected from this cohort on the Social Responsiveness Scale confirmed the lack of validity for at least this measure of ASD in this population [ 50 ].…”

Strong evidence for genotype–phenotype correlations in Phelan-McDermid syndrome: results from the developmental synaptopathies consortium

“…Defects in SHANK3 have been identified as a relatively common cause of ASD ( 6–8 ), and ASD is frequent in PMS. The most recent estimates based on prospective assessments in large samples using gold-standard diagnostic tools such as the Autism Diagnostic Interview-Revised (ADI-R; ( 9 )), the Autism Diagnostic Observation Schedule, second edition (ADOS-2; ( 10 )) and the Diagnostic and Statistical Manual for Mental Disorders, fifth edition (DSM-5) criteria ( 11 ) establish the prevalence of ASD to be 58% ( 12 ). Global developmental delays and/or ID are present in the vast majority of individuals diagnosed with PMS thus far.…”

Best practice assessments for autism spectrum disorders in schools

“…The SRS‐2 is often used to characterize ASD‐related symptoms, and using a cutoff score of 70 is considered to have a sensitivity of 0.78 and specificity of 0.94 for ASD (Constantino & Gruber, 2005). However, individuals with high levels of behavior problems or profound Intellectual Disability are more likely to receive higher scores (ratings indicative of ASD) on the SRS‐2 (Gergoudis et al, 2020; Hus et al, 2013). Consequently, practitioners should interpret findings with caution in students with possible co‐occurring conditions.…”