Screening, Assessment, and Diagnosis of Autism Spectrum Disorders in Young Children: Canadian Best Practice Guidelines
Nachshen, J., Garcin, N., et al. (2008).
Montreal, QC (Canada): Miriam Foundation, 1-89.
This clinical practice guideline provides recommendations for early screening, assessment, and diagnosis of young children, birth to five years of age, on the autism spectrum.
Miriam Foundation (Canada)
"The use of the [<em>Gilliam Autism Rating Scale</em>] GARS and the [<em>Autism Behavior Checklist</em>] ABC is not recommended [due to their low sensitivity rates]" (p. 80). The GARS was reported to have a low sensitivity of 0.48 and the ABC was reported to have a low sensitivity range of 0.31 to 0.71.
"The [Modified Checklist for Autism in Toddlers] is an appropriate parent-report tool for use in second-level screening due to its ease of administration ... It is recommended that the follow-up interview is administered in conjunction with the parent-report questionnaire to increase sensitivity" (p. 80 ). Reported sensitivity ranged from 0.77 to 0.97 and reported specificity ranged from 0.27 to 0.99.
<p>"Interdisciplinary teams are recommended above multidisciplinary teams [to assess for autism spectrum], but either is preferable to a single-practitioner approach" (p. 81). Members of the team may include some of the following professionals:</p>
<ul>
<li>audiologists;</li>
<li>speech-language pathologists;</li>
<li>behavioral specialists/early interventionists;</li>
<li>educational specialists;</li>
<li>occupational therapists;</li>
<li>psychologists; and</li>
<li>social workers.</li>
</ul>
<p>"Referral for audiology assessment should be made concurrently with referral to an interdisciplinary [autism spectrum] ... assessment team, unless an audiologist is part of the team" (p. 80). "An audiology consultation is needed to assess for and rule out the presence of [hearing loss] .... An assessment of hearing and vision is needed to determine [the] presence of co-occurring sensory difficulties" (p. 83).</p>
"If a parent brings up a concern about his or her child's development, particularly concerns related to communication and social behaviour, appropriate investigations should be conducted and/or a referral should be made to appropriate services.... A 'wait and see' approach is not appropriate" (p. 79).
"The [<em>Checklist for Autism in Toddlers</em>] CHAT is the most researched screening tool and may be tentatively recommended for second level screening. The Denver modification is tentatively recommended to increase sensitivity without a loss to specificity" (p. 80). Reported sensitivity for the CHAT ranged from 0.18 to 0.65; with the Denver modification, sensitivity ranged from 0.75 to 0.85. Reported specificity for the CHAT ranged from 0.98 to 1.0; with the Denver modification, specificity ranged from 0.92 to 1.0.
The <em>Autism Diagnostic Interview-Revised</em> (ADI-R) and the <em>Autism Diagnostic Observation Scale</em> (ADOS), in combination with clinical judgement, is the current gold standard for the diagnosis of autism spectrum disorders. "However, a lack of ADI-R, ADOS data should not prevent a child from receiving much needed services if a diagnostician with sufficient expertise conducts the assessment" (p. 82).
<p>"Referral to a speech-language pathologist for assessment and intervention should be made concurrently with referral to an interdisciplinary [autism spectrum] ... assessment team, unless the SLP is part of the team" (p. 80).</p>
<p>"A speech-language pathology assessment may be necessary to assess for other communication or language disorders.... Children [on the autism spectrum] ... require a full assessment of communication abilities for appropriate treatment planning" (p. 82).</p>
"The [<em>Childhood Autism Rating Scale</em>] may also be used in diagnostic assessments" (p. 82).
<p>"Developmental surveillance should be a continuous process undertaken by physicians and other professionals in contact with young children, with reference to developmental milestones and with knowledge of the symptoms of [autism spectrum]" (p. 20). One missed milestone may not be cause for concern, but more caution is advised when two or more of the following milestone have not been met:</p>
<ul>
<li>"Diminished, atypical, or no babbling by 12 months</li>
<li>Diminished, atypical, or no gesturing (e.g., pointing, waving bye-bye) by 12 months</li>
<li>Lack of response to name by 12 months</li>
<li>No single words by 16 months</li>
<li>Diminished, atypical, or no two-word spontaneous phrases (excluding echolalia or repetitive speech) by 24 months</li>
<li>Loss of any language or social skill at any age [and/or]</li>
<li>Lack of joint attention" (p. 79).</li>
</ul>
When conducting the parent interview and assessment, consider the family's cultural, ethnic, and religious backgrounds.
"The [<em>Screening Tool for Autism in Two-Year-Olds</em>] is recommended as a second-level screener for use by professionals trained in its administration in distinguishing autistic disorder from other developmental delays" (p. 80). The reported sensitivity ranged from 0.83 to 0.92 and the reported specificity ranged from 0.85 to 0.86.
