ACQ_Vol_11_no_3_2009

Figure 1. District referral pathway

differential diagnosis of clients presenting with possible communication disorders, PDD and/or mental health disorders. This pathway uses the Autism Diagnostic Observation Schedule-Generic (ADOS-G) as a clinical diagnostic utility because of its sensitivity and specificity in this client group (Sikora et al., 2008). Autism Diagnostic Observation Schedule-Generic (ADOS-G) The ADOS-G is a semi-structured, standardised assessment of communication, social interaction, play and imaginative use of materials. It is used as a diagnostic tool alongside clinical and contextual information to identify if an individual warrants a diagnosis of autism or ASD. The ADOS-G is a test that shows excellent inter-rater reliability, test-retest reliability, internal consistency, and generally good agreement across domains with the highest agreement being for communication/social interaction and lowest agreement being for repetitive behaviours/stereotyped interests (Lord, Rutter, DiLavore, & Risi, 2003). However, the use of the ADOS-G is clearly related to the skill of the examiner and requires specific training and practice (Lord et al., 2000). The standardised activities in the ADOS-G allow for the observation of behaviours that have been identified as important to the diagnosis of autism and ASD at different developmental levels and chronological ages. It assesses what the participant “doesn’t do” which is as important as what he or she “does do” in the specific domains of communication, social interaction and social reciprocity, play, creativity and imagination, and stereotyped behaviours and restrictive interests. The examiner focuses on the quality of the interactions and the capacity of the child to use communication and knowledge about relationships to complete the tasks. Four modules are available, with one of those administered based on level of expressive language and chronological age. Each item is scored on a scale from 0 (no abnormal behaviour) to 3 (markedly abnormal behaviour). The derived scores on each of these main areas are compared to specified cut-off scores. If a child scores higher than the cut-off score for example, this indicates that the child has scored within the range that a high proportion of participants with autism and similar levels of expressive language have scored. ADOS-G does not provide a diagnosis on its own and involves the assessment of the interaction between the child and examiner across a range of social conditions or tasks. It can help inform clinical judgment and should never be the sole piece of evidence for an ASD diagnosis. The “thresholds” for a diagnosis are derived simply from “optimising statistics” (aiming to identify true positives) and not from clinical judgment. Consequently, it makes good clinical sense that, as clinicians are faced with a large body of literature concerned with language, communication, and behaviour in the area of PDD, they use an ADOS-G in conjunction with other tests, observation schedules and interviews when making a differential clinical diagnosis. Referral pathway for ADOS-G Figure 1 shows the standard clinical process for assessment of PDD within CYMHS. Each community and hospital CYMHS clinic maintains an ADOS-G subteam consisting of speech pathologists, psychologists, and/or social workers. Each member initially receives specialist training which is maintained at intermittent stages to ensure the reliability and viability of the test results obtained.

Intake team May or may not identify PDD.

Initial case presentation May or may not identify PDD. Determine range of assessments and timing. Clinical case conference Review of checklists, observations, collateral from school and social settings, formal and informal test results. Refer to the ADOS team if indicated.

ADOS-G team Assist with the differential diagnosis.

Process: 1. Young people with symptoms or previous diagnosis of PDD who meet the CYMHS intake criteria may be identified or flagged for possible ADOS referral at intake. They will undergo the standard initial clinical assessment and case presentation. 2. Clinical case conference is the forum for discussion regarding the range of possible assessments and diagnostic processes. • Where the young person clearly does have PDD and treatment planning and intervention is unambiguous, an ADOS-G assessment would not be indicated. • Where the young person does not have a diagnosis of PDD, but has features which might suggest this, further assessment or information gathering may be recommended. The range and timing of this will be determined at a case conference. These range across a number of domains and formats and include: i. checklists, ii. observation, iii. gathering collateral information, i.e. in-depth developmental interviews, school and other relevant sources, iv. formal assessments such as cognitive or language. • This information is reviewed in the presence of the consultant child psychiatrist and team leader, and if the information suggests a possible diagnosis of PDD, then referral to ADOS-G using the ADOS referral form is made. 1 3. An appointment at CYMHS is then made for the client. The test takes one hour to complete and all scoring is completed immediately by two to three trained staff. Differential diagnosis is made by the team at case review. Feedback is then given to the family with a written report for the file and family. Additional reports may be provided as necessary. Case vignette Sam (a hypothetical client) attends high school. He had significant history of anxiety and sporadic attendance at school due to school refusal for past two years. He also had a diagnosis of language impairment and non-verbal learning disorder. CYMHS treatment goals focused on reducing anxiety and improving psychological functioning (especially in

1. Please contact the author for a copy of the referral form.

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ACQ Volume 11, Number 3 2009

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