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Friday, May 8, 2009
Northwest Hall (Chicago Hilton)
3:30 PM
Background:
The Childhood Autism Rating Scale (CARS; Schopler, Reichler & Renner, 1988) is a behaviour observation scale in which a trained observer rates the child’s behaviour on 15 dimensions or symptoms that are related to autism. The measure produces a total score which places the child into one of three categorical diagnoses: not autism, mild/moderate autism or severe autism. This measure has been shown to have important clinical and research utility and is widely used in the diagnosis, treatment planning, and treatment evaluation of children with Autism Spectrum Disorders (ASDs; Magyar & Pandolfi, 2007; Perry, Condillac, Freeman, Dunn Geier & Belair, 2005; Weiss, 1999). Three studies have examined the underlying factor structure of the CARS. DiLalla and Rogers (1994) found that the CARS items loaded onto three separate factors. In their 1999 study Stella, Mundy and Tuchman, study found a five-factor solution, while Magyar and Pandolfi (2007) found four factors. The varying results in these previous studies may be accounted for by differences in their sample characteristics, including; sample size, ages, and diagnoses. The present study examined this issue in a very large multi-site sample.
Objectives:
The underlying factor structure of the CARS was investigated in a large sample of individuals diagnosed with an ASD. This analysis was intended to help determine whether, according to the CARS, there is symptom coherence across individuals with autism, indicating a general autism factor or whether there are distinct and independent groups of symptoms as previous research on this measure has suggested. This study will further help to elucidate the underlying dimensions of the clinically defined syndrome of autism.
Methods:
This was a file review study involving multiple settings across Ontario, Canada. The CARS was administered to the participants within the context of routine clinical assessments by a team of trained clinicians who have demonstrated high interrater reliability. Data were complied and analyzed for 958 participants.The participants were separated into two groups based on age.
Results:
The results suggest that for the older group of 130 adolescents and young adults with ASD (mean age of 10.42 years) the 15 items of the CARS load onto three separate factors. However, it was found that for the younger group, which was composed of 828 younger children with an ASD (mean age of 4.33 years), the CARS items load onto two factors. Specific items loadings for each factor will be reported and the results compared to those from the previous CARS factor analytic studies. In addition, factor scores will be examined as a function of cognitive level.
Conclusions:
These results suggest that the characteristics of autism, as measured by the CARS, may be different in adolescents and young adults than in younger children and that autism is not necessarily a unitary construct. Possible explanations for these findings will be discussed.
The Childhood Autism Rating Scale (CARS; Schopler, Reichler & Renner, 1988) is a behaviour observation scale in which a trained observer rates the child’s behaviour on 15 dimensions or symptoms that are related to autism. The measure produces a total score which places the child into one of three categorical diagnoses: not autism, mild/moderate autism or severe autism. This measure has been shown to have important clinical and research utility and is widely used in the diagnosis, treatment planning, and treatment evaluation of children with Autism Spectrum Disorders (ASDs; Magyar & Pandolfi, 2007; Perry, Condillac, Freeman, Dunn Geier & Belair, 2005; Weiss, 1999). Three studies have examined the underlying factor structure of the CARS. DiLalla and Rogers (1994) found that the CARS items loaded onto three separate factors. In their 1999 study Stella, Mundy and Tuchman, study found a five-factor solution, while Magyar and Pandolfi (2007) found four factors. The varying results in these previous studies may be accounted for by differences in their sample characteristics, including; sample size, ages, and diagnoses. The present study examined this issue in a very large multi-site sample.
Objectives:
The underlying factor structure of the CARS was investigated in a large sample of individuals diagnosed with an ASD. This analysis was intended to help determine whether, according to the CARS, there is symptom coherence across individuals with autism, indicating a general autism factor or whether there are distinct and independent groups of symptoms as previous research on this measure has suggested. This study will further help to elucidate the underlying dimensions of the clinically defined syndrome of autism.
Methods:
This was a file review study involving multiple settings across Ontario, Canada. The CARS was administered to the participants within the context of routine clinical assessments by a team of trained clinicians who have demonstrated high interrater reliability. Data were complied and analyzed for 958 participants.The participants were separated into two groups based on age.
Results:
The results suggest that for the older group of 130 adolescents and young adults with ASD (mean age of 10.42 years) the 15 items of the CARS load onto three separate factors. However, it was found that for the younger group, which was composed of 828 younger children with an ASD (mean age of 4.33 years), the CARS items load onto two factors. Specific items loadings for each factor will be reported and the results compared to those from the previous CARS factor analytic studies. In addition, factor scores will be examined as a function of cognitive level.
Conclusions:
These results suggest that the characteristics of autism, as measured by the CARS, may be different in adolescents and young adults than in younger children and that autism is not necessarily a unitary construct. Possible explanations for these findings will be discussed.