Psychometric properties, factor structure and cross-cultural validity of the quantitative CHecklist for autism in toddlers (Q-CHAT) in an Italian community setting

Background: In the past decade, several screening instruments have been developed to detect toddlers at risk for autism, both in clinical and unselected samples.We aimed to assess the validity and cross-cultural stability of the Quantitative CHecklist for Autism in Toddlers (Q−CHAT), a quantitative and normally distributed measure of autistic traits, during routine paediatric developmental surveillance in a large Italian community of toddlers. Methods: A group of n = 2400 unselected Italian toddlers were screened by paediatricians during routine well−CHild visits between 18 and 24 months,in three Italian regions, representative of the North, Centre and South of Italy. The psychometric properties and factor structure of the Q−CHAT were explored and compared with published literature from Asia and the UK. Results: The total Q−CHAT scores in our sample confirmed a normal distribution. Mean Q−CHAT scores across regions were consistent with those reported in UK studies and likewise, a gender effect was found, with boys scoring higher than girls.We also found a remarkable consistency with the three-factor structure of the Asian Q−CHAT. Internal consistency was acceptable for both the Q−CHAT total score and the three factors. Conclusions: Our results confirm the dimensional distribution of autistic traits and related symptoms in unselected populations across different cultures. The Q−CHAT is a valid and reliable dimensional screening instrument to be used within a routine paediatric setting during well-child assessments.The main normative data and factor structure replicated in our sample