Validity and reliability of the Childhood Autism Rating Scale with autistic adolescents.

The validity and reliability of the Childhood Autism Rating Scale (CARS) for autistic adolescents was tested. In the first study, CARS scores for autistic children and adolescents (matched on nonverbal IQ, sex, and ethnicity) were compared. In the second study, a group of nonautistic, handicapped adolescents were administered the CARS and these scores were compared with those of a group of autistic adolescents (matched on age, nonverbal IQ, sex, and ethnicity). The CARS clearly discriminated the two adolescent groups, suggesting that the scale may be an adequate measure of autism in adolescence. Although the CARS total score did not discriminate the younger from older autistic subjects, some interesting age-related differences emerged for specific items. A recommendation is made for elimination of one of the items on the CARS that negatively correlates with the CARS total score for both autistic groups.