Sunday, January 13, 2013

Test Review: Social Responsiveness Scale, Second Edition (SRS-2)

The second edition of the widely administered Social Responsiveness Scale (SRS-2; Constantino & Gruber, 2012) maintains continuity with the original instrument as an efficient quantitative measure of the various dimensions of interpersonal behavior, communication, and repetitive/stereotypic behavior characteristic of autism spectrum disorders (ASD). The SRS-2 extends the age range from 2.5 years through adulthood. There are now four forms, each consisting of 65 items and for a specific age group: Preschool Form (ages 2.5 to 4.5 years); School-Age Form (4 to 18 years); Adult Form (ages 19 and up); and Adult Self-Report Form (ages 19 and up). Nationally representative standardization samples were collected to support each form. These samples consist of a total of 4,709 ratings of 1,963 individuals: 474 ratings of 247 preschool children, 2,025 ratings of 1,014 school-age children, and 2,210 ratings of 702 adults.
The individual items of the SRS-2 show strong parallels across forms. While most of the 65 items are the same, some were changed and reference activities and social behavior that are specific and appropriate to the ages covered by their respective form. Only the School-Age form is unchanged in its item content from the first edition of the SRS. Each item is scored on a 4 point scale Likert-scale: 1 (“not true”); 2 (“sometimes true); 3 (often true); and 4 (“almost always true”). Scores are obtained for five Treatment Subscales: Social Awareness; Social Cognition; Social Communication; Social Motivation; and Restricted Interests and Repetitive Behavior. There are also two DSM-5 Compatible Subscales (Social Communication and Interaction and Restricted Interests and Repetitive Behavior) that allow comparison of symptoms to the new DSM-5 ASD diagnostic criteria.  
Interpretation is based on a single score (Total Score) reflecting the sum of responses to all 65 SRS questions which serves as an index of severity of social skills across the autism spectrum. The SRS-2 Total score is expressed in raw and T-scores. Raw scores are converted to T-scores for gender and respondent. T-score guidelines provide interpretive language applicable to the specific age rages covered by the various forms (preschool, school-age, and adult). A total T-score of 76 or higher is considered severe and strongly associated with clinical diagnosis of Autistic Disorder. T-scores of 66 through 75 are interpreted as indicating Moderate deficiencies in reciprocal social behavior that are clinically significant and lead to substantial interference in everyday social interactions, whereas T-scores of 60 to 65 are in the Mild range and indicate mild to moderate deficits in social interaction. T scores of 59 and below are considered to be within typical limits and generally not associated with clinically significant ASD. A Profile Sheet for each form provides T-score results and a brief summary statement to facilitate interpretation and discussion of results. Raters can complete the 65 items in approximately 15 to 20 minutes. Scoring and graphing can be completed in approximately 5 to 10 minutes. The manual provides a series of case examples to illustrate application of the SRS-2 at different points across the lifespan (preschool, school-age, and adult). Although the SRS-2 is relatively easy to administer and score, interpretation and application of the results require professional training and experience in child development, psychology, or education.
Psychometric Characteristics
More than 40 research studies and independent resources support the diagnostic validity of SRS-2 and the instrument’s application in a wide variety of clinical and educational contexts. Based on research analyses, a total raw score cutpoint value of 70 is associated with a sensitivity value of .78 and specificity value of .94 for any ASD (autistic disorder, Asperger's disorder, or PDD-NOS) in unselected general-population groups. In terms of positive predictive value (PPV), 93% of children whose scores fall above this cutpoint will, upon completion of a comprehensive assessment, receive a diagnosis of ASD. In most clinical and school settings, raw scores at or above 85 from two separate informants provide very strong evidence of ASD. In a large clinical sample (School-Age Form), ROC (receiver operating characteristics) analyses indicate an area under the curve (AUC) of .968 and a sensitivity and specificity value of .92 at a raw score of 62. This suggests that the SRS-2 is a robust instrument for discriminating between individuals with ASD and those unaffected by the condition. Large samples also provide evidence of good interrater reliability, high internal consistency, and convergent validity with the Autism Diagnostic Interview-Revised (ADI-R), Autism Diagnostic Observation Schedule (ADOS), and Social Communication Questionnaire (SCQ).
A significant strength of the SRS-2 is its facility in quantitatively measuring autistic traits and symptoms across the complete range of severity (mild to severe). This is especially important when identifying the more subtle characteristics of autism and more capable and less severely affected individuals with ASD (without intellectual disability). The SRS-2 forms should also be useful for quantifying response to intervention/treatment over time. Extending the age range of the SRS-2 adds to its versatility as a screening and diagnostic measure of symptoms associated with ASD. The Preschool and Adult Forms afford multiple perspectives throughout the life span and provide important tools for both clinicians and researchers to assess these populations. The subscales corresponding to the two symptom domains: Social Communication (SCI) and Restricted Interests and Repetitive Behavior (RRB) will also align the SRS-2 with the recently approved DSM-5 criteria for Autism Spectrum Disorder and Social Communication Disorder. Because a majority of independent research has been limited to the School-Age form, studies are needed to provide further information relative to the diagnostic validity of the Preschool and Adult Forms. Likewise, research is needed to examine the relationship between social impairment and intellectual disability and the more severe forms of ADHD. In sum, the SRS-2 can be used confidently in school and clinical contexts as an efficient measure of ASD symptomatology and severity. However, the results of questionnaire measures should not replace clinical assessment and must be integrated with information from different sources. The SRS-2 should be used within the context of a comprehensive evaluation, including developmental history and assessment of intellectual, language, and adaptive behavior functioning.
Constantino, J. N., & Gruber, C. P. (2012). Social Responsiveness Scale, Second Edition. Los Angeles, CA: Western Psychological Services.
Wilkinson, L. A. (2016). A Best Practice Guide to Assessment and Intervention for Autism Spectrum Disorder in Schools (2nd Ed.). London, UK: Jessica Kingsley Publishers. 

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