The Quantitative Checklist for Autism in Toddlers (QCHAT): Validation of a Screening Instrument in Italy.
Early screening and detection of autism spectrum disorders (ASD) is crucial to enable early effective interventions and to improve long-term outcomes. Several studies in the past two decades have focused on the development of early ASD screening tools that have been tested in both the general population and at-risk children, in population-based and clinically-referred samples. The Quantitative CHecklist for Autism in Toddlers (QCHAT) is a parent-report questionnaire that quantifies autistic traits along a continuum at 18-30 months (Allison et al., J Autism Dev Disord 2008). The QCHAT discriminated between a group of unselected children and those having a diagnosis of ASD. Furthermore it showed that autistic traits are continuously distributed in the general population of toddlers.
To examine the distribution of Q-CHAT scores in (a) an unselected sample of toddlers (TD), (b) in a sample of toddlers and young children with Developmental Delay (DD), and (c) in a sample of young children already diagnosed with an ASD, in three regions (Piemonte, Toscana and Sicilia), representative of the North, Centre and South of Italy.
A group of n=318 children took part in the study and the QCHAT was administered. These comprised n=129 TD children (mean age=32.9, SD=9.4 months), n=50 DD children (mean age=27.6, SD=8.3 months), and n=139 ASD children (mean age=31.6, SD=8 months). TD children were recruited in mainstream nursery schools in the three regions involved in the study. ASD and DD children were tested at the clinical facilities within the Autism Centre of the NHS in the province of Cuneo (Piemonte), the Scientific Foundation “Stella Maris” in Pisa (Toscana) and the University Hospital “G. Martino” in Messina (Sicilia) respectively. The Autism Diagnostic Observation Schedule - Second Edition (ADOS-2) and the Griffith’s Mental Development Scale (GMDS) were used as part of the diagnostic assessment in the DD and ASD groups. The three groups were matched for age and no region differences were found for age, gender, and QCHAT total scores. A between group analysis of variance was conducted to assess group differences in the QCHAT total scores, accounting for gender effects and gender by group interaction. No differences in Developmental Quotient scores were found in the ASD and DD groups (F (2,196)=1.66, p<0.2).
A main effect of group was observed on the QCHAT scores, with the ASD group (mean = 39.4 (SD = 13.1)) scoring significantly higher than the DD (mean = 27.1 (SD = 6.3) and TD (mean = 21.1 (SD = 6.6) group respectively (F (2,312) = 76.4, p<0.001). No gender and group by gender interaction was found (F (1,312)=0.62, p=0.4 and F (2,312)=0.01, p=0.99).
The QCHAT was able to discriminate between a group of young children with a diagnosis of an ASD and unselected children, as well as between children with developmental delay. This replicates previous findings in a different cultural setting. A large-scale population-based screening study in different regions of Italy is underway to assess the validity of the Q-CHAT as a screening instrument for ASD.