International Meeting for Autism Research (London, May 15-17, 2008): Confirmation of the ADOS Module 1 Revised Algorithm in Young Children with Autism Spectrum Disorder

Thursday, May 15, 2008

Champagne Terrace/Bordeaux (Novotel London West)

9:30 AM

A. P. Thompson , Offord Centre for Child Studies, McMaster University, Hamilton, ON, Canada

E. Duku , Offord Centre for Child Studies, McMaster University, Hamilton, ON, Canada

S. Georgiades , Offord Centre for Child Studies, McMaster University, Hamilton, ON, Canada

T. A. Bennett , Offord Centre for Child Studies, McMaster University, Hamilton, ON, Canada

P. Szatmari , Offord Centre for Child Studies, McMaster University, Hamilton, ON, Canada

S. E. Bryson , Pediatrics and Psychology, Dalhousie University/IWK Health Centre, Halifax, NS, Canada

E. Fombonne , Head of the Department of Psychiatry, McGill University, Montreal, QC, Canada

P. Mirenda , Educational and Counseling Psychology and Special Education, University of British Columbia, Vancouver, BC, Canada

W. Roberts , Department of Pediatrics, Hospital for Sick Children & Bloorview Kids Rehab, University of Toronto, Toronto, ON, Canada

I. M. Smith , Dalhousie University, Halifax, NS, Canada

T. Vaillancourt , Offord Centre for Child Studies, McMaster University, Hamilton, ON, Canada

J. Volden , Speech Language Pathology, University of Alberta, Edmonton, AB, Canada

C. Waddell , Simon Fraser University

L. Zwaigenbaum , Department of Pediatrics, University of Alberta, Edmonton, AB, Canada

P. In ASD Study Team

Background: The Autism Diagnostic Observation Schedule (Lord et al., 2000) assesses communication, social and play skills, and restrictive/repetitive behaviours in the diagnosis of ASD. Recently, Gotham et al. (2007) revised the algorithms for Modules 1, 2 and 3 based on factor analytic evidence of two domains (Social Affect, SA; Restricted, Repetitive Behaviours, RRB). Two 14-item Module 1 algorithm versions were developed depending on language ability (no words; some words) in a sample with an average age of 56 months (range=14-144).
Objectives: To test the proposed revision of the ADOS Module 1 algorithm in a population of preschoolers with ASD.
Methods: Module 1 data were available on 193 children with ASD participating in a Canadian longitudinal study (mean age=36.6 months, mean mental age=18.9 months). Due to our small sample size, it was not possible to analyze the “no words” and “some words” algorithms separately. Instead, we used only the 12 items common to both algorithms (4 language-based items were excluded). Confirmatory factor analysis was used to examine whether the 2-factor model met the acceptable model fit criteria in our sample.
Results: The model fit was good (RMSEA=0.06; CFI=0.98). The correlation between the SA and RRB factors (r=-0.15) was lower than for the “no words” (r=0.49) and “some words” (r=0.59) algorithms proposed by Gotham et al. (2007).
Conclusions: The revised 2-factor model of the ADOS Module 1 algorithm developed in older children was confirmed in our sample of preschoolers with ASD, even though only the 12 items common to both Module 1 algorithms were included in the analyses. The lack of correlation between SA and RRB factors suggests some level of independence. Further research of this longitudinal cohort is necessary to determine if the correlation between the factors changes over time.

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