Best Practice Review: Childhood Autism Rating Scale, Second Edition (CARS 2)

The Childhood Autism Rating Scale, Second Edition (CARS 2), consists of two 15-item rating scales completed by the practitioner and a Parent/Caregiver Questionnaire. The Standard Version Rating Booklet (CARS 2-ST) is equivalent to the original CARS and is used with children younger than 6 years of age and those with communication difficulties or below-average cognitive ability. The High-Functioning Version Rating Booklet (CARS 2-HF) is an alternative for assessing verbally fluent children and youth, 6 years of age and older, with average or above intellectual ability. The Questionnaire for Parents or Caregivers (CARS 2-QPC) is an unscored questionnaire designed to obtain pertinent developmental information from parents or caregivers. 

The CARS 2-ST and CARS 2-HF each include 15 items addressing the following functional areas:

• Relating to People
• Imitation (ST); Social-Emotional Understanding (HF)
• Emotional Response (ST); Emotional Expression and Regulation of Emotions (HF)
• Body Use
• Object Use (ST); Object Use in Play (HF)
• Adaptation to Change (ST); Adaptation to Change/Restricted Interests (HF)
• Visual Response
• Listening Response
• Taste, Smell, and Touch Response and Use
• Fear or Nervousness (ST); Fear or Anxiety (HF)
• Verbal Communication
• Nonverbal Communication
• Activity Level (ST); Thinking/Cognitive Integration Skills (HF)
• Level and Consistency of Intellectual Response
• General Impressions

Items on the Standard form duplicate those on the original CARS, while items on the HF form have been modified to reflect current research on the characteristics of higher functioning children with autism spectrum disorder (ASD). To complete the ratings on the CARS 2-HF, the professional must have convergent information from MULTIPLE sources such as direct observation, parent and teacher interviews, prior assessments of cognitive functioning and adaptive behavior, and information from the Questionnaire for Parents or Caregivers (CARS 2-QPC). Ratings are based not only on frequency of the behavior in question, but also on its intensity, atypicality, and duration. Rating values for all items are summed to produce a Total Raw Score. Each form includes a graph that allows the practitioner quickly convert the Total Raw Score to a standard score or percentile rank (based on a clinical sample of individuals diagnosed with autism spectrum disorders). 

The psychometric properties of the CARS 2-HF indicate a high degree of internal consistency and good interrater reliability. Validity information reports an overall discrimination index value of .93, with sensitivity and specificity values of .81 and .87, respectively. The HF form also demonstrates a relatively strong relationship with the “gold standard” Autism Diagnostic Observation Schedule (ADOS).

The following are critical features of the CARS 2-HF.

1. Parents and teachers should NOT be asked to complete the CARS 2 forms. Only well-informed professionals should complete the ratings.

2. The CARS 2 should NOT be used for screening in the general school-age population.

3. The practitioner must have a good understanding of the criteria for making the ratings and be in a position to collect information from multiple sources (direct observation, parent and teacher reports, prior assessments and clinical impressions).

4. The ratings from the CARS 2 should be considered as only one part of a multimodal, multidisciplinary decision-making process in the identification of children with ASD.

5. Direct observation and a developmental history MUST always be included in the assessment process.

6. Scores on the CARS 2 are interpreted relative to the level (severity) of autism-related behaviors compared to a clinical sample of individuals diagnosed with autism, NOT the typical individual.

In summary, The CARS 2-HF represents an important alternative that will be welcomed by school-based professionals such as school psychologists and speech/language pathologists. It is a sensitive and reliable instrument that will find a place in the school-based professional’s assessment “Tool Box.” Given the dramatic increase in the numbers of students being referred for screening and assessment, the CARS 2-HF is a useful instrument that helps quantify the level of symptom severity and importantly, assist with intervention and program planning. The CARS 2-HF scores are particularly helpful in identifying more capable children with autism spectrum disorder. Of course, the CARS 2 is not intended to be and should not be used as the sole instrument in making diagnostic or classification decisions. An example of a comprehensive assessment battery can be found in A Best Practice Guide to Assessment and Intervention for Autism Spectrum Disorder in Schools (2nd Edition).

Schopler, E, Van Bourgondien, M. E., Wellman, G. J., & Love, S. R. (2010). Childhood Autism Rating Scale, Second Edition. Los Angeles, CA: Western Psychological Services.

Lee A. Wilkinson, PhD, is a licensed and nationally certified school psychologist, and certified cognitive-behavioral therapist. He is author of the award-winning books, A Best Practice Guide to Assessment and Intervention for Autism and Asperger Syndrome in Schools and Overcoming Anxiety and Depression on the Autism Spectrum: A Self-Help Guide Using CBT. He is also editor of a text in the APA School Psychology Book Series, Autism Spectrum Disorder in Children and Adolescents: Evidence-Based Assessment and Intervention in Schools. His latest book is A Best Practice Guide to Assessment and Intervention for Autism Spectrum Disorder in Schools (2nd Edition)