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J Autism Dev Disord (2011) 41:302310 DOI 10.1007/s10803-010-1054-3
ORIGINAL PAPER
Comparing Autism, PDD-NOS, and Other Developmental
Disabilities on Parent-Reported Behavior Problems: Little
Evidence for ASD Subtype Validity
Anne V. Snow Luc Lecavalier
Published online: 16 June 2010 Springer Science+Business Media, LLC 2010
Abstract Studies on the distinction between Autistic Disorder (AD) and Pervasive Developmental Disorder Not Otherwise Specied (PDD-NOS) have been inconclusive. This study examined the validity of PDD-NOS by comparing it to AD and other developmental disorders (DD) on parent-reported behavior problems. Fifty-four children with PDD-NOS were individually matched on age and non-verbal IQ to 54 children with AD and 54 children with DD. Groups were compared on select subscales of the Child Behavior Checklist. High rates of psychopathology were observed in both ASD groups. The only difference between PDD-NOS and AD groups was higher scores in the PDDNOS group on two items measuring Anxiety/Depression. Cognitive functioning may be a more salient variable than subtype when studying psychopathology in individuals with ASDs.
Keywords Autism PDD-NOS Subtypes
Classication Validity Behavior problems
Introduction
The acknowledgement of the wide variation in the clinical expression of autistic disorder (AD) has been one of the most important developments in the eld of autism in the last 20 years. To account for this range of presentation, classication systems have broadened to include autism spectrum disorder (ASD) subtypes. The most frequently diagnosed subtype is pervasive developmental disorder, not
otherwise specied (PDD-NOS), yet it is the least well characterized (Fombonne 2005). Current denitions of PDD-NOS are ambiguous. The DSM-IV-TR (APA 2000) does not provide guidelines for which or how many symptoms should be endorsed for a diagnosis of PDDNOS. It is currently a subthreshold diagnosis that is used when the individual does not meet the diagnostic criteria for AD.
The current denition of PDD-NOS compromises the reliability and validity with which it is diagnosed. Studies on diagnostic agreement of ASDs suggest that expert clinicians reach much higher agreement when discriminating ASDs from other disorders than when attempting to distinguish between subtypes, especially when differentiating PDD-NOS from other ASDs (e.g., Mahoney et al. 1998; Volkmar et al. 1994). These studies suggest that current diagnostic criteria for PDD-NOS may not be sufciently reliable for diagnostic or research purposes.
Establishing the validity of diagnostic categories...