Screening Vs

......when experience matters

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Screening vs. Diagnosis
of
Autism Spectrum Disorders

We frequently get asked about the diagnostic process in evaluating children for possible Autism Spectrum Disorders. There is a lot of confusion on this topic that I hope that we can help provide some useful information in clarifying for parents and others. First, there is no "medical" test for Autism, PDD-NOS, or Aspergers Syndrome. The diagnostic process is one of a trained professional interviewing caregivers, observing the child, and having the child try to do some specific things to help clarify the child's abilities and developmental sequences for the professional. Much of the confusion in this area comes from many people misusing screening devices as diagnostic instruments. Here is some information that I recently offered to the Georgia Autism Listserv in an effort to help clarify this issue.

A variety of devices are used to diagnose Autism Spectrum Disorders. Many of the devices that are commonly mentioned and used are not truly diagnostic devices but are screening devices. While this distinction may be a bit academic for lots of folks it is an often overlooked and VERY important distinction. The CHAT which was mentioned here is a terrific device developed in the UK to screen for ASDs and to be used principally by Home Visit Nurses who see EVERY newborn in their own home in the UK. It is meant to include MORE children in the category of ""Possibly Autistic" than really have Autism. The idea behind a screening device is that you want to include every possible child/person for further more specific and accurate testing and not include anyone that is clearly not exhibiting any signs or symptoms of the diagnosis. This sort of device can be administered by someone with basic training in the area and therefore means that more children will at least have the question asked in a structured way. If the child exceeds the criteria for the device then they should be referred to a fully-trained and licensed professional with experience in diagnosing and working with children who can conduct a full assessment/evaluation using more sophisticated devices requiring both more time and more skill/training to use properly.

Currently, per the National Academy of Sciences report "Educating Children with Autism" available for review online through our website, the "Gold Standard" for diagnosing ASD is a combination of the ADI-R and ADOS. The ADI-R is the Autism Diagnostic Interview - Revised and is a developmental and behavioral history done by a trained professional with the parent/caregiver that takes 90-120 minutes. The ADOS is the Autism Diagnostic Observation Schedule and is a structured series of interactions and observations of the child in a variety of situations and at various tasks. The combination of an extensive history interview with the person that knows the child best and a structured observation of key skills by a fully-trained professional forms the best basis for formulating a diagnosis that exists today.

There are a variety of other devices that exist - CARS, GARS-II, ASIEP-II, etc., etc., etc. but many of these are much more limited and superficial in what information they gather. For example, the ASIEP-II is the Autism Screening Instrument for Educational Planning - 2nd Edition and is a terrific in assisting in the development of specific targets to be worked on at school in the IEP - hence its name. However, it is not truly a diagnostic device and is more geared toward what to do once the diagnosis has been established. The CARS is particularly popular with School Psychologists but it is based on out-dated diagnostic criteria, been demonstrated to be subject to significant bias, and includes items in the diagnostic formulation that are neither part of the eligibility requirements or diagnostic requirements. These devices are also much more easily administered and less time consuming for those administering them.

Another important note, the more limited devices are of less utility when the question is less about classic autism and more about other presentations like PDD-NOS, Aspergers Syndrome, or a non-ASD diagnosis. Screening devices are a terrific set of tools for use by minimally trained people trying to decide how to assist a child by sending them (or not) for much more extensive evaluations. They were never intended to be the end-point in the diagnostic process because they are designed to over-include children in the "possibly-autistic" category and provide no information on treatment formulation - what treatments might be best or most likely to help this specific child.

We typically utilize the ADI-R & ADOS in combination in our clinic. Despite concerns expressed above, we also use the CARS because we have had schools express concern when it is absent even though the ADOS & ADI-R provide significantly more precision and detail already. In addition other language devices and treatment formulation devices are employed in the evaluation process which are not diagnostic like the ABLLS. When the question is possible Aspergers Syndrome we utilize the ADOS (it has 4 modules or levels and 3 & 4 are appropriate for questions about possible Aspergers) in addition to a variety of very specialized devices like the EYES Test, FACES Test, PLSI, TOPL, CASL, and other non-verbal communication assessments in addition to devices that look at interests, behavior patterns, etc.

I hope that this information helps. At the Autism Spectrum Assessment Program we believe that there is an important role for precision diagnostics - it is to give us the best starting place to form a treatment plan that is most likely to help the specific child. Diagnostics should have no other purpose than to fully inform treatment. However, we also realize that eligibility issues are involved in the diagnositc process. This is why we conduct comprehensive evaluations that include traditional cognitive, academic, achievement, adaptive, and other testing in our evaluations. I'm always happy to answer questions about this process - its what we do every day!

Robert W. Montgomery, Ph.D.
Director, Autism Spectrum Assessment Program
Reinforcement Unlimited
Licensed Psychologist & Board Certified Behavior Analyst
P. O. Box 1572 - 335 Parkway 575 Suite 220
Woodstock, GA 30188
http://www.behavior-consultant.com
(770) 591-9552 - (770) 516-4191 Fax

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