ADOS Abuse

ADOS Abuse
(And not just the ADOS)….
Some days reading outside records is bad for my blood pressure. Today was one of them. My patient — let’s call him Brian (actually, a composite patient based on several individual case files) – was brought to me by his parents for evaluation of disruptive behavior at school.
As a toddler Brian’s speech was delayed, and once he did begin speaking he had verbally repetitious behavior, asking the same question over and over, or reciting stock phrases from movies. Presently, he is able to converse better with adults than peers. He frequently misunderstands or misperceives verbal and nonverbal cues. He is emotionally labile, and “Goes from zero to 60 in the blink of an eye.” He has no true friends. Starting at 12 months, and continuing thereafter, he has manifested an intense interest a succession of things: initially “obsessed” with Buzz Lightyear, followed by an interest in the states of the Union, wanting to know his parents’ favorite state, then moving on to the solar system (“he could tell you everything about Jupiter”). His obsessive interests have since waned, although he remains rigid and perfectionistic.

Brian attends 1st grade in a typical setting. His teacher wrote: Brian is a kind boy… Brian is very much a rule-follower… very much wants to do everything perfectly… ” The Pupil Services Team was consulted because of recurrent task refusals and minor altercations with peers. Testing revealed average WISC-IV and academic achievement scores. Behavioral rating scales completed by the teacher noted “very elevated” scores in the areas of Hyperactivity/Impulsivity, Aggression, and Peer Relations. The ADOS 2 was administered, and Brian did not meet threshold criteria for ASD. The school psychologist stated that the ADOS “ruled out ASD,” and an “educational diagnosis” of ADHD was given.

This would be laughable if it weren’t so damaging. The ADOS (Autism Diagnostic Observation Schedule) is “a semi structured assessment of social interaction, communication, play, and imaginative use of materials for individuals who may have autism or other autism spectrum disorder (ASD)…the goal of the ADOS is to provide a hierarchy of “presses” (social structures) that elicit behaviors in standardized contexts relevant to ASD.” http://bestpracticeautism.blogspot.com/2012/01/best-practice-review-autism-diagnostic.html. Clinical experience working with children with ASD is “recommended,” but not mandatory.

A positive result on the ADOS has become the de facto ticket of admission into academic research on ASD: Researchers from all parts of the country want to be sure that they are looking at comparable samples of children; a positive result on the ADOS assures some level of comparability. Researchers don’t mind if the ADOS misses a few kids, because their job is research, not clinical care. Care providers, however, have a different set of obligations – to find and serve all children with ASD. Read the rest of this entry »

DSM5: The case for double standards

In my last post I talked about the inappropriate application of double standards in the DSM, as reflected in the preferential treatment given to behavioral over biological markers of mental disorders: as “porous” as behavioral markers are, the editors of DSM5 enshrine them as the “best” way of identifying mental disorders. On the other hand, here is no place in DSM5 for biological data, unless these data are “incontrovertible.” This double standard reflects the historical background of the DSM, and the difficulty in making institutional change.
There is, however, one arena in which the editors of the DSM ought to have advocated for a double standard, but failed to do so: Actually using the DSM to make a diagnosis.

Before discussing DSM5, we need to have a little discussion about medical screening. Don’t panic; I’ll leave out the math. (Readers who want a more detailed discussion can go here: http://en.wikipedia.org/wiki/Sensitivity_and_specificity )
Let’s discuss a hypothetical disease, which is considered to exist if the individual’s clinical or laboratory findings are outside of a defined “normal range.” Let’s also say we already have decided what test we’re going to use; now our job is to decide where to set the cutoff for “normal” vs. “abnormal.” If we’re lucky, the range of normal values and the range of abnormal values do not overlap, and we can set our cutoff value in between them, as in Case A. Persons with values to the left of the line will screen “negative,” and we can be 100% reassured that they do not have the disease. Persons whose values lie to the right of the cutoff are deemed “positive,” and we can be 100% certain that they have the disease. There are, in fact, some conditions that work this way: Inborn errors of metabolism (PKU, urea cycle disorders, etc.) are a good example. Babies with inborn metabolic errors have lab values that are hundreds or thousands of times elevated compared to the normal range.

Case A: Normal and abnormal values do not overlap, and we can set a cutoff value in between them. 100% of the subjects who screen “negative” (i.e. pass the screening test) are free of disease, and 100% of subjects who screen positive (fail the screening test) actually have the disease.

Most of the time, however, the “healthy” and “disease” groups overlap, as in Case B. There is no place we can set the cutoff value to cleanly separate them, no matter how good our test. We will inevitably generate some False Negatives (persons who pass the test, but actually have disease), and False Positives (persons who fail the test, but are actually healthy).

Case B. Clinical or laboratory values for the two populations overlap. Persons lying to the left of the cutoff fall into two sub-categories: True Negatives, and False Negatives (FN in the figure). Persons lying to the right of the line likewise fall into two sub-categories: True Positives, and False Positives (FP in the figure).

The question of where to set the cutoff comes up all the time in medicine — and the answer is “It Depends.” If you are conducting research on a particular disorder, you want to be sure that your research subjects all have the condition you’re interested in. You don’t want any False Positives watering down your study sample, so you will set your cutoff point as high as possible. (Case C). You will wind up generating a lot of false negatives (people who test negative  but really have the disorder), but that’s not a problem in this situation, because your mission is research, not clinical care.

Case C. Researchers interested in studying a disorder may set the cutoff very high, to assure that their study sample is composed completely of subjects who have the disease. The tradeoff for reducing False Positives to zero is the generation of a large number of False Negatives.

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