Assessing symptoms during comprehensive interventions for young children with autism spectrum disorder: Development and preliminary analysis of the Autism Behaviour Coding System (ABCS).

The aims of this paper are to present the Autism Behaviour Coding System (ABCS), a novel, video-based observational instrument for assessing core autism symptoms during intensive early interventions in autism spectrum disorder (ASD), to provide preliminary data on its psychometric characteristics and to discuss its clinical utility. Video recordings of child-therapist interactions during the 'Frühintervention bei autistischen Störungen' (FIAS) were coded by treatment-independent raters who were blind with respect to the temporal order of the sequences. We assessed inter-rater reliability using intra-class correlations (ICCs). Mean ICCs ranged from 0.85 to 0.90. We analysed the sensitivity of the ABCS to change by comparing the change in ABCS scores with the change in a validated external measure of level of functioning (Developmental Disorder-Child-Global Assessment of functioning Scale, DD-C-GAS) in a sample of 15 children who received intensive treatment. Both the ABCS and DD-C-GAS indicated that the intervention improved symptoms. The ABCS has promise as a research instrument and has good to excellent inter-rater agreement and sensitivity to intervention-related changes. This pilot study suggests that the ABCS may be useful as an objective method of assessing the proximal effects of therapy in young children with ASD.