When our 18-month old son had his recent check-up, we were given a short form to complete prior to the appointment.  That form was an autism screening tool called the Modified Checklist for Autism (M-CHAT), one of the most widely used and studied instruments that exists for this purpose.  This rating scale works pretty well and has undoubtedly been responsible for improving the early detection of autism:  a crucial step in getting important treatment to begin as soon as possible.

Like all instruments, it is not perfect, and the designers have now developed a new and improved version of the scale called the M-CHAT revised/follow-up (R/F).   The hope is that this new form will replace the old one in primary care offices across the country.

What makes the new scale different is not just some changes in the questions but perhaps more importantly how it is scored and what to do about those scores.  Based on what parents write down on the M-CHAT-R/F, the total score is placed into one of three categories – low, medium, and high risk.  The instructions for what to do for the low and high risk toddlers are pretty straightforward.  Those at high risk should be sent for a more in-depth autism evaluation right away and those at low risk don’t need further action, other than a repeat M-CHAT-R/F if they are not yet 24 months old. 

The middle risk kids are a bit trickier.  Now, the instructions are that pediatricians and other primary care clinicians are supposed to go through a series of scripted questions that delve into more detail about those items that are raising a red flag for autism.  Such a process could take about 15 minutes or so and potentially could be done by someone other than the physician.  Based on those questions, another score is generated and if that score is also above the cut-off then the full evaluation is recommended.

This new additional step for medium risk kids was shown in a recent study to cut down on the number of “false-positive” kids who initially screened in but don’t wind up being diagnosed with autism.  The million dollar question in my mind, however, is will this new step really happen in a busy primary care office, and what will occur if it doesn’t?

Interviews containing scripted questions to help make a diagnosis of various psychiatric disorders have been around for decades and are considered “gold standard” measures that are required in research studies.  However, they are uncommonly used in everyday practice by psychiatrists and even more rarely used in primary care settings.  Consequently, it seems quite likely that many primary care clinics will struggle with this new recommended step.  I posed this practical question to the lead author of the M-CHAT, Diana Robins PhD, at George State University.  In an email, she agreed that this issue is appearing more and more problematic and wants to look at it in more detail.

If primary care clinicians decide not to adopt this new follow-up procedure, the instrument could lose some of its discriminative power.  Further, it seems like several scenarios could result (each with its own downfall).

  1. Doctors could just stick to the old M-CHAT (with the loss of the improved instrument resulting in less accurate autism detection)
  2. They could plan to do the follow-up step but often not actually get to it (resulting in a delay of the screening process)
  3. They could group the medium risk kids into the low risk group (which potentially could result in some autistic kids not being formally evaluated until they are older)
  4. They could group the medium risk kids into the high risk group (which could lead to more evaluations and longer waits for kids who would not end up being diagnosed with autism but require formal evaluations to verify this)

None of these options seems ideal.  My guess at this point is that the adoption of the new M-CHAT will be quite slow, especially with this new step in place.  Public health programs will likely continue to target autism screening as an important issue and try to find a procedure that will work without making it too arduous for those who need to implement it.

@copyright by David Rettew, MD

David Rettew is author of Child Temperament: New Thinking About the Boundary Between Traits and Illness and a child psychiatrist in the psychiatry and pediatrics departments at the University of Vermont College of Medicine.

Follow him at @PediPsych and like PediPsych on Facebook.

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