Age at initial diagnosis of autism spectrum disorders: a retrospective comparison of screening techniques between the southern and northwestern regions of Switzerland.

Aims: Early diagnosis of autism spectrum disorders (ASD) offers the possibility of early intervention and, in turn, gains in adaptive behaviour, language and cognition. The aim of the present study was to analyse whether age at diagnosis of autism spectrum disorders decreased in two regions of Switzerland from 2006 to 2016 following the implementation of different screening and referral techniques. In southern Switzerland, systematic paediatric screening using the Modified Checklist for Autism (M-CHAT) in toddlers was implemented in 2013, whereas in northwestern Switzerland, periodic trainings were used to increase paediatrician awareness of ASD. We investigated which method was associated with a younger average age at diagnosis.
Methods: We conducted a retrospective, two-centre study searching clinical records of children and adolescents (aged 0-16 years) diagnosed with ASD in two neuropaediatric departments at Swiss hospitals between January 2006 and December 2016. All patients were diagnosed via a standardised evaluation based on two approved diagnostic tests: the Autism Diagnostic Observation Schedule-Second Edition (ADOS-2) and the Autism Diagnostic Interview-Revised (ADI-R).
Results: In southern Switzerland, training and subsequent widespread use of the M-CHAT among paediatricians appeared to contribute to a significantly younger age at diagnosis. Age at diagnosis did not significantly decrease during the same period in northwestern Switzerland.
Conclusion: Our results point to the possibility of successfully reducing age at diagnosis in specific geographic areas through the implementation of screening questionnaires, such as the M-CHAT, at year 2 well-baby visits.