International Meeting for Autism Research (London, May 15-17, 2008): Factors Associated With Timing Of Diagnosis In A Large Sample Of Preschool Children With ASD

Saturday, May 17, 2008

Champagne Terrace/Bordeaux (Novotel London West)

9:30 AM

M. Steiman , Autism Clinic, Montreal Children's Hospital, Montreal, QC, Canada

R. Simon , Autism Program, Montreal Children's Hospital, Montreal, QC, Canada

E. Fombonne , Head, Division of Child Psychiatry, McGill University, Montreal, QC, Canada

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

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

W. Roberts , Hospital for Sick Children, 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

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

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

Background: The availability and efficacy of early intervention programs render early diagnosis of ASD important. However, long intervals still persist between first parental concerns and final diagnostic confirmation of ASD. Objectives: To examine the age range at which young preschoolers with ASD are diagnosed and to identify factors associated with age at diagnosis.
Methods: The sample comes from a multisite longitudinal Canadian study (Pathways in ASD) and consisted of 274 preschoolers (mean age at study entry: 39.2 months; 232 males). For analyses purposes, baseline data on diagnostic and psychometric measures were used.

Results: Mean age at diagnosis was 37.9 months, with no gender differences. Preschoolers with an ADOS score consistent with autistic disorder were diagnosed 3.3 months earlier (p=.025) than those in the ASD range. Children with a Merrill-Palmer–Revised score of 70 or above were diagnosed significantly later (mean age = 42.6 months) than those with scores below 70 (mean age = 36.8 months). Correlations were not significant between age and CBCL Internalizing, Externalizing, or Total scores; RBS-R total score; Parental Stress Index scores; VABS composite scores; or ADI-R Social and Non-verbal scores. Small to moderate correlations were found between SRS Total scores (r=.17), ADI-R Repetitive scores (r=.23), ADOS Play scores (r=-0.53) and 3 ABC subscales (Irritability: r=.18; Hyperactivity: r=.19; Inappropriate Speech: r=.40). Socio-demographic variables (family structure, household income, and mother’s education, employment status and ethnicity,) were not related to age at diagnosis. Broadly similar results emerged on analyses conducted on the delay between age at first parental concern and age at diagnosis (mean delay=19 months). Multivariate analyses will evaluate the effect of individual predictors of age and diagnostic delay. Conclusions: Diagnosis occurred after the third birthday, 19 months after parents first concerns. As these delays are compounded by waits for treatment they must be reduced to improve outcomes.

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