Clinical investigations in Autism Spectrum disorder – a retrospective study of the Service des Troubles du Spectre de l’Autisme et Apparentés paediatric cohort and tentative guideline

Background: Autism spectrum disorder is a neurodevelopmental disorder diagnosed nowadays in very early in childhood. The genetic aetiology of this disorder is now well described. ASD might present with co-occurring neurological disorders like epilepsy, neuro- cutaneous syndrome, or neuro-metabolic disorder (some of which are treatable), or co-morbid conditions like sleep disorders, language delay... which should be investigated in case of specific clinical suspicion. There exist no consensus recommendations about how to assess aetiology, co-occurring disease or co-morbid conditions in young children with ASD. Aim: This monocentric retrospective study aims at establishing the yield of the various complementary examinations carried out on a paediatric cohort with ASD and to compare the practices at the STSA-A in CHUV Switzerland with the literature. Eventually, we propose a tentative guideline diagram to orientate the clinical investigations in children with ASD. Methods: Literature was searched via PubMed, books and Google Scholar. We collected data using REDCap on a cohort of patients aged between 0 to 18 years old referred to the STASA- A diagnostic centre between 2017-2018. We performed descriptive statistics and compared with existing literature. Results: During 2017-2018, 174/180 children had a DSM-V diagnosis of ASD. The majority was aged 2-4 years old. 137/174 were male and 37/174 were female patients (M/F 3.7:1). Among them, 62/174 were assessed with clinical investigations; with32/174 in genetic, 52/174 by EEG, 26/174 in metabolic and 24/174 by MRI. Interestingly, among the 52 EEG performed, 60% were considered mildly abnormal with sleep patterns. Conclusion: The yield of the clinical investigations performed in our service is lower than the literature description. This might be explained by the small sample size of our cohort, the starting clinical activity in a newly launched centre dedicated to ASD, and by the fact that transversal collaborations with other services were under construction (genetics, metabolic disorder unit). There is still few literature about recommendations on how to perform clinical investigations in children with ASD. Based on the STSA-A cohort description and literature related to ASD co-morbidities and global developmental delay, we established a tentative guideline dedicated to clinical investigations in children with ASD