Diagnosing autism spectrum disorders in pre-school children using two standardised assessment instruments: The ADI-R and the ADOS

The reliable diagnosis of Autism/Autism Spectrum Disorder in pre-school children is important for access to early intervention and for accurate ascertainment for research. This paper explores the combined use of two standardised assessment instruments-the Autism Diagnostic Interview Revised (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS)-in a large sample of pre-school children. The children were recruited to research studies, and a 'best estimate' clinical diagnosis reached. The findings show good agreement between the instruments especially for children with core Autism. The instruments appear to have a complementary effect in aiding diagnosis and confirm the importance of a multi-disciplinary assessment process with access to information from different sources and settings. The presence of repetitive behaviours during the ADOS appeared of diagnostic significance.