Part II: A Closer Look
If the screening shows concerns, what is your plan of care? What if it does not?
If the M-CHAT-R Total Score is in the High-Risk category for ASD (total score of 8-20 points), refer for a comprehensive diagnostic evaluation and eligibility evaluation for early intervention or conduct the Follow-Up interview to gain clarity on at-risk responses.
If the M-CHAT-R Total Score is in the Medium-Risk for ASD (total score of 3-7 points), conduct the Follow-Up interview. The Follow-Up Interview is a semi-structured interview administered to a caregiver of any child who failed an M-CHAT-R screening. The interview includes a script to review all the failed items, asks for specific examples, and offers multiple examples against which to judge whether the child fails or passes the item. If the Follow-Up Interview raises concerns, or if the child fails any two items on the Follow-Up, referral for comprehensive evaluation is warranted.
If the M-CHAT-R Total Score is in the Low-Risk for ASD (total score of 0-2 points) AND the provider and parents have no concerns, then continue developmental surveillance at all subsequent health supervision visits.
Value in doing a Follow-Up Interview
What is the value in doing a Follow-Up interview after the initial M-CHAT-R questionnaire?
The Follow-Up questions help clarify answers and obtain additional information for at-risk items. The Follow-Up questions improve the ASD detection rate and reduce the number of screen positives when compared to the M-CHAT-R alone.
False Negatives / Positives
What would contribute to a false negative screen? A false positive screen?
- A parent or caregiver who does not fully comprehend the items might provide responses based on experience and perceptions that may not reflect true behavior. The Follow-Up questions are designed to help clarify questions and responses. Providers can help illiterate or low-literacy parents complete the paper form.
- Completing the M-CHAT-R at an early age (younger than the recommended age) might also contribute to a false negative or false positive screen. Approximately 30% of children with ASD show a period of typical development followed by plateau or regression, and screening too early might miss some of these later-onset children.
- A child with other forms of developmental delay or other atypical forms of development might exhibit some ASD symptoms which would result in a false positive screen. Similarly, toddlers with severe developmental delays or impairments in vision and/or hearing may have a false positive screening for ASD.
- Some children with ASD, particularly those with more intact language and intellectual development, may have more subtle symptoms at an early age. Thus, mild symptoms and even an absence of symptoms at 18 months does not “rule out” a later diagnosis of ASD. Ongoing surveillance and follow-up are essential, particularly for children who are referred as a result of early concerns but initially are not diagnosed with ASD.
Clinical judgment should be considered when assessing a child. Even if a screen is negative, if there are professional or parental concerns, the child should be referred for a comprehensive evaluation and to early intervention.