Most parents to children with Autism Spectrum Disorder (ASD) can report concerns about their child's development within the first year of life. In spite of this, children with ASD are rarely diagnosed before the age of 3–4 years. Early identification allows early intervention, which seems to be substantial for improvement of core behavioural symptoms in children with ASD. The Child Behaviour Checklist for ages 1½ to 5 (CBCL/1½–5) have shown promising utility for early detection of children with ASD.

This study will estimate the positive predictive value of CBCL/1½–5 Pervasive Developmental Problems (PDP) scale in a 2 phase screening study. Furthermore, it will analyse the stability of the CBCL/1½–5 PDP-score in pre-school children from 2½ to 5 years.

The present study aims to validate CBCL/1½–5 for early screening of ASD in a general population sample.

Parents, enrolled in the Odense Child Cohort (OCC), answered the CBCL/1½–5 when the child reached 27 months of age. Parents with children above the age of four and a raw score ≥5 (90th percentile) on the PDP scale, received the Social Responsiveness Scale (SRS) questionnaire. Children with a high score on the SRS were invited to a clinical examination consisting of ADOS and ADI-R. Children in OCC were re-assessed with CBCL/1½–5 again at age five years.

Results will be presented at the EPA conference 2017 in Florence.

The results may contribute to enhance the outcome of treatment by detecting children with ASD at an earlier age.

The authors have not supplied their declaration of competing interest.