Applying Item Response Theory Modeling to Identify Social (Pragmatic) Communication Disorder




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Social (pragmatic) communication disorder (SPCD) is a new diagnostic category (American Psychiatric Association, 2013) that describes individuals with severe deficits in social communication who do not also meet the criteria for repetitive, restricted behaviors and interests (RRBI) that would qualify them for a diagnosis of Autism Spectrum Disorder (ASD). Prior to the introduction of the SPCD category, relatively few studies provided scientific evidence on interventions for these individuals. The need to identify people with SPCD so that evidencebased interventions for them can be designed and tested was an important motivation for this study. In this study, we aimed to identify test items from a widely used screening test, the Social Communication Questionnaire-Lifetime (SCQ-L; Rutter, Bailey, & Lord, 2003) to differentiate people with SPCD from typical controls and those with ASD. We took a cost-efficient approach by applying item response theory modeling to a large archive of responses to the SCQ-L. As a result, we found that a 7-item social communication measure was diagnostically informative, having a Youden’s Index value of .70 and both sensitivity and specificity values greater than 0.80. A 5-item RRBI measure had a lower Youden’s Index value (.40), with acceptable specificity (0.80) but low sensitivity (0.59). Finally, we tested the classification accuracy of these item sets in a smaller cross-validation data set that yielded comparable point estimates for sensitivity and specificity for the optimal social communication and RRBI measures. This study provides a list of test items that can be used to develop a screening test for SPCD. This study also illustrates the value, and promise, of using archival data and IRT modeling approach. The findings of several key steps of the IRT modeling, such as measuring the assumption of unidimensionality and DIF analysis, highlight an issue in test development due to reverse coded items and suggest that people with social communication deficits may differ both quantitatively and qualitatively from typical individuals in the social communication domain.



Item response theory, Autism spectrum disorders, Autism--Diagnosis, Communication--Social aspects, Psychological tests


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