Diagnostic tests for autism spectrum disorder (ASD) in preschool children

This is a protocol for a Cochrane Review (diagnostic). The objectives are as follows: Primary objectives To evaluate the diagnostic accuracy of widely used ASD diagnostic tools (specifically CARS, GARS, ADOS, ADI-R, DISCO, 3di) in preschool children, compared with multidisciplinary team clinical judgement. We aim to: summarise sensitivity, specificity, and other accuracy measures for each ASD diagnostic tool; and for studies that compare two or more tools within the same study, describe and compare their diagnostic accuracy. To identify if any combination of diagnostic tools has greater diagnostic test accuracy than each single tool. We aim to: describe combined diagnostic test accuracy within a single study; and compare combined diagnostic test accuracy to individual test accuracy from primary objective 1a. Secondary objectives To assess whether there is different diagnostic test accuracy for subgroups such as intellectual disability, language level, setting, prospective versus retrospective, DSM diagnostic classification and specific ages (within the preschool age range).