Usefulness of current autism diagnostic or screening assessment tools in adults with intellectual disability (ID): systematic review of literature

Purpose The purpose of the study is to identify and ascertain if there were any validated tools for diagnosing or screening autism spectrum disorder in adults with ID. The estimated prevalence of intellectual disability (ID) in the general population is about 10.37/1,000 population (Maulik et al., 2011). In total, 1 out of 4 individuals with ID suffers from an autism spectrum disorder (ASD) (Sappok et al., 2010). Early diagnosis and support for ASD is key to having a good quality of life. The diagnosis of ASD in people with an ID presents its own challenges and it is likely under-identification of ASD amongst adults with ID by about 20% to 30% (Emerson and Baines, 2010). Design/methodology/approach Studies were selected based on the following criteria: studies that reported either screening or diagnostic tools for ASD, participants had an ID i.e. a mean IQ of <70, adults i.e. participants were >18 years of age at the time of entry to the study and articles reported either sensitivity, specificity or area under the curve. Relevant studies that were published up to January 2020 were identified from EMBASE, PsychINFO, CINAHL and PubMed. In total, 75 papers were identified of which 15 papers met the criteria. Findings The screening or diagnostic tools currently in use is dependant on the degree of ID. A number of the tools had good psychometric properties and utility when used in people with specific degrees of ID or when used in combination with another screening or diagnostic tool. The authors could not identify a diagnostic tool that could be used across all levels of severity of ID unless used in combination. Hence, concluded that there is a need for a diagnostic tool with good psychometric properties for the assessment of ASD in adults with all degree of ID within a reasonable time period without the need for an additional tool to be used in conjunction. Originality/value Currently, the "gold standard" for diagnosing ASD is a lengthy and time-consuming process carried out by trained multi-disciplinary team members who assess historical, behavioural and parent/carer report to arrive at a diagnosis. There are a number of tools that have been developed to aid diagnosis. However, it is important to identify the tools that can optimise the procedures and are also time-efficient.