Differential Diagnosis of Autism Spectrum Disorders and Other Developmental Delays Using the BASC-2 PRS-P

Background:

The Behavior Assessment System for Children, Second Edition (BASC-2; Reynolds & Kamphaus 2004) is a behavior rating scale commonly used in elementary and preschool settings. In addition to ratings of behavior such as hyperactivity, withdrawal, social skills, and adaptive functioning, the BASC-2 includes a Developmental Social Disorders content scale that evaluates the presence of behaviors commonly associated with pervasive developmental disorders, such as self-stimulation, withdrawal and poor socialization. Previous research by Volker et al. (2010) demonstrated that the DSD content scale reliably distinguished children with High-Functioning Autism Spectrum Disorders from typically developing peers.

Objectives:  

The aim of the current study is to extend the research of Volker et al. (2010) to a lower age group by comparing the BASC-2 PRS-P scores of toddler and preschool-age children diagnosed with different developmental disorders.

Methods:

The BASC-2 PRS-P scores of 39 children ages 24 to 50 months were analyzed, including 11 children diagnosed with Autistic Disorder (AD; 8 boys, 3 girls; mean age=32.73 months, SD=8.33), 11 children diagnosed with Global Developmental Delay (GDD) and/or Language Delay (LD; GDD/LD group had 5 boys, 6 girls; mean age=28.91 months, SD=5.19), and 17 children diagnosed with Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS; 11 boys, 6 girls; mean age=34.00 months (SD=9.63).

Results:  

For the Developmental Social Disorder (DSD) scale, mean T-scores for the AD, PDD-NOS, and GDD/LD groups were 70.27, 60.06, and 61.18, respectively. It should be noted that the mean score for AD group was within the “clinically significant” range according to the BASC-2 manual, T-score > 70, whereas the mean T-scores for both the PDD-NOS and GDD/LD groups fell in the “at risk” range, T-score > 60. A one-way analysis of variance revealed significant differences between T-scores for the three groups F(2, 37)=5.01, p=.012. Post hoc analyses utilizing independent t-tests revealed a significantly higher score for the AD (mean T-score=70.27) group on the DSD scale compared to the GDD/LD group (mean T-score=61.18), t(20)=2.968 p=.008, and compared to the PDD-NOS group (mean T-score=60.06), t(25)=2.943 p=.007. Children in the AD group also obtained a significantly higher score (mean T-score=64.18) on the Attention Problems scale than the GDD/LD group (mean T-score=54.82), t(20)=2.631 p=.016. There were no significant differences in scores between the GDD/LD group and the PDD-NOS group t(25)=-.300 p=.767.

Conclusions:  

Preliminary data analyses suggest that the Developmental Social Disorders scale of the BASC-2 PRS-P accurately distinguishes between children with Autistic Disorder and those diagnosed with PDD-NOS or other developmental delays. These results suggest that the BASC-2 PRS-P may be a useful tool as part of a comprehensive evaluation for developmental disorders in toddler and preschool age children. It is interesting to note that the PDD-NOS group was distinguished from the AD group on this measure, given that the differences in phenotypic expression of autistic symptoms between these groups may not be that striking in toddlers. Future analyses should disaggregate samples by age (i.e., 2 year olds versus 4 year olds) to determine if these differences remain significant across age groups within the Preschool form.