Best Practice in Screening Students for Autism Spectrum Disorders (ASD)

By Lee Wilkinson posted 02-28-2012 09:32

  

 
There has been a dramatic worldwide increase in reported cases of autism over the past decade. Today, autism spectrum conditions affect approximately 1 to 2 % of the school-age population. Yet, compared to population estimates, identification rates have not kept pace in our schools. It is not unusual for school age children with milder forms of autism (e.g., Asperger syndrome, pervasive developmental disorder-NOS, high-functioning autistic disorder) to go undiagnosed. Consequently, it is critical that school-based educational support personnel (e.g., special educators, school counselors, speech/language pathologists, social workers, and school psychologists) give greater priority to case finding and screening to ensure that children with milder forms of ASD are identified and have access to the appropriate intervention services (Wilkinson, 2010).

Screening and Identification

Developing screening tools to identify the milder forms of ASD tends to be especially difficult because the autism spectrum is comprised of a wide range of impairment without clear-cut boundaries. Until recently, there were few validated screening measures available to assist school professionals in the identification of students with the core ASD-related behaviors. However, our knowledge base is expanding rapidly and we now have reliable and valid tools to screen and evaluate children more efficiently and with greater accuracy.

The following tools have demonstrated utility in screening for ASD in educational settings and can be used to determine which children are likely to require further assessment and/or who might benefit from additional support. All measures have sound psychometric properties (e.g., diagnostic validity), are appropriate for school-age children, and time efficient (10 to 20 minutes to complete). Training needs are minimal and require little or no professional instruction to complete. However, interpretation of results requires familiarity with ASD and experience in administering, scoring, and interpreting psychological tests.

The Autism Spectrum Rating Scales (Short Form) (ASRS; Goldstein & Naglieri, 2009) is a norm-referenced tool designed to effectively identify symptoms, behaviors, and associated features of ASD in children and adolescents from 2 to 18 years of age. The ASRS can be completed by teachers and/or parents and has both long and short forms. The Short form was developed for screening purposes and contains 15 items from the full-length form that have been shown to differentiate children diagnosed with ASD from children in the general population. High scores indicate that many behaviors associated with ASD have been observed and follow-up recommended.

The Social Communication Questionnaire (SCQ; Rutter, Bailey, & Lord, 2003), previously known as the Autism Screening Questionnaire (ASQ), is a parent/caregiver dimensional measure of ASD symptomatology appropriate for children of any chronological age older than four years. It is available in two forms, Lifetime and Current, each with 40 questions. Scores on the questionnaire provide a resonable index of symptom severity in the reciprocal social interaction, communication, and restricted/repetitive behavior domains and indicate the likelihood that a child has an ASD.

The Social Responsiveness Scale (SRS; Constantino & Gruber, 2005) is a brief quantitative measure of autistic behaviors in 4 to 18 year old children and youth. This 65-item rating scale was designed to be completed by an adult (teacher and/or parent) who is familiar with the child’s current behavior and developmental history. The SRS items measure the ASD symptoms in the domains of social awareness, social information processing, reciprocal social communication, social anxiety/avoidance, and stereotypic behavior/restricted interests. The scale provides a Total Score that reflects the level of severity across the entire autism spectrum.

A Multi-Step Screening Strategy

The ASRS, SCQ, and SRS can be used confidently as efficient first-level screening tools for identifying the presence of the more broadly defined and subtle symptoms of higher-functioning ASD in school settings. School-based professionals should consider the following multi-step strategy for identifying at-risk students who are in need of an in-depth assessment.

Step one. The initial step is case finding. This involves the ability to recognize the risk factors and/or warning signs of ASD. All school professionals should be engaged in case finding and be alert to those students who display atypical social and/or communication behaviors that might be associated with ASD. Parent and/or teacher reports of social impairment combined with communication and behavioral concerns constitute a “red flag” and indicate the need for screening.  Students who are identified with risk factors during the case finding phase should be referred for formal screening.

Step two. Scores on the ASRS, SCQ, and SRS may be used as an indication of the approximate severity of ASD symptomatology for students who present with elevated developmental risk factors and/or warning signs of ASD. However, as with all screening tools, there will be some false negatives (children with ASD who are not identified). Thus, children who screen negative, but who have a high level of risk and/or where parent and/or teacher concerns indicate developmental variations and behaviors consistent with an autism-related disorder should continue to be monitored, regardless of screening results.        

Step three. Students who meet the threshold criteria in step two may then referred for an in-depth assessment. Because the ASRS, SCQ, and SRS are strongly related to well-established and researched gold standard measures and report high levels of sensitivity (ability to correctly identify cases in a population), the results from these screening measures can be used in combination with a comprehensive developmental assessment of social behavior, language and communication, adaptive behavior, motor skills, sensory issues, and cognitive functioning to aid in determining eligibility for special education services and as a guide to intervention planning (National Research Council 2001; Wilkinson, 2010).

Limitations

Although the screening instruments reviewed in this article can be recommended as reliable and valid tools for identifying children across the broad autism spectrum, they are not without limitations. Some students who screen positive will not be identified with an ASD (false positive). On the other hand, some children who were not initially identified will go on to meet the diagnostic and/ or classification criteria (false negative). Therefore, it is especially important to carefully monitor those students who screen negative so as to ensure access to intervention services. A screening tool’s efficiency will also be influenced by the practice setting in which it is used. Autism-specific tools are not currently recommended for the universal screening of typical school-age children. Focusing on case finding and children with identified risk-factors and/or developmental delays increases predictive values and results in more efficient screening (Wilkinson, 2010).

Concluding Comments

Compared with general population estimates, children with mild autistic traits appear to be an underidentified and underserved population in our schools (Wilkinson, 2010). There are likely a substantial number of children with equivalent profiles to those with a clinical diagnosis of ASD who are not receiving services. Research indicates that outcomes for children on the autism spectrum can be significantly enhanced with the delivery of intensive intervention services (National Research Council, 2001). However, intervention services can only be implemented if students are identified. Screening is the initial step in this process. School professionals should be prepared to recognize the presence of risk factors and/or early warning signs of ASD, engage in case finding, and be familiar with screening tools in order to ensure children with ASD are being identified and provided with the appropriate programs and services (Wilkinson, 2010).

References provided upon request.

A comprehensive discussion of the screening algorithm and step-by-step assessment guidelines are available from:

Wilkinson, L. A. (2010). A Best Practice Guide to Assessment and Intervention for Autism and Asperger Syndrome in Schools. London: Jessica Kingsley Publishers.

© Lee A. Wilkinson, PhD

http://bestpracticeautism.com

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