M-CHAT Autism Screen

The Modified Checklist for Autism in Toddlers is a parent completed screening questionnaire for autism spectrum disorder in children aged 16 to 30 months. It asks about social communication, joint attention, play and sensory behaviour.

A follow up interview is used for children who screen positive, and this improves the specificity of the screen by identifying false positives.

Usage. It is used at routine developmental reviews, and in toddlers with parental concern about social communication.

Indications. Routine screening at 18 and 24 months, and at other reviews where there is concern about social communication or play.

Preparation and technique. A parent completes the questionnaire, which takes about 5 to 10 minutes. Items are answered as yes or no, and a follow up interview is administered to parents whose responses score positive.

Contraindications and precautions. The screen is not valid for children who are too young or too old for the age range. Parental literacy, language and cultural expectations affect responses.

Interpretation.

• A total score over the cut off, or failure of critical items, indicates a positive screen.
• A positive screen is followed by the follow up interview, and children who remain positive are referred for specialist assessment.
• A negative screen does not exclude autism spectrum disorder, particularly if the parent or clinician remains concerned.

Causes of a positive screen. Autism spectrum disorder, global developmental delay, language disorder, hearing impairment, and social communication difficulties from other causes.

Critical values and findings needing immediate action. A child with loss of language or social skills requires prompt medical review, since regression is not typical of autism screening findings alone.

Limitations and artefacts. The screen has moderate sensitivity and specificity, so many positive screens are false positives without the follow up interview. Parental report is subjective. The screen is not a diagnosis.

Follow up tests. Specialist diagnostic assessment, audiology to exclude hearing impairment, and developmental assessment for global delay.

Special groups. Preterm children are assessed with corrected age. Children with known developmental conditions are assessed with tools suited to their needs.