ACQ_Vol_11_no_3_2009

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ACQ Volume 11, Number 3 2009 153
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
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. 1. Please contact the author for a copy of the referral form.
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.
Figure 1. District referral pathway