Psychometric properties of the Autism Spectrum Disorder in Adults Screening Questionnaire (ASDASQ) in a sample of Italian psychiatric outpatients

Background: The present study aimed to examine the reliability and validity of the Italian version of the Autism Spectrum Disorder in Adults Screening Questionnaire (ASDASQ), a screening tool for autism spectrum disorder (ASD) among psychiatric outpatients. Methods: We recruited 340 subjects via an outpatient psychiatric service in Italy. Forty-eight had a diagnosis of ASD, confirmed after a comprehensive clinical assessment and the administration of the Autism Diagnostic Observation Schedule-2 (ADOS-2). The remaining 292 participants had other diagnoses, confirmed after a careful psychiatric evaluation and the administration of the Structured Clinical Interview for DSM-5 (SCID-5). The ASDASQ was administered to contact clinicians of each subject. Results: The ASDASQ showed outstanding accuracy (AUC = 0.96) in discriminating between ASD and non-ASD patients, with good sensitivity (0.85) and specificity (0.92). Agreement with clinical diagnosis was substantial (k = 0.68). Internal consistency of the tool was good (Cronbach's alpha = -0.82), while intra- (ICC = 0.97) and inter-rater reliability (ICC = 0.92) were excellent. We found also a moderate correlation between ASDASQ and ADOS-2 scores in the ASD sample (r = 0.56). Conclusion: Our findings suggest that the ASDASQ, in the Italian adaptation, may be considered a quick, simple, and effective tool to screen for ASD among psychiatric outpatients. Further studies are needed to evaluate its utility in other clinical settings.