Screening tools for Autism Spectrum Disorder, used with people with an Intellectual Disability: A systematic review

Background
A diagnosis of autism spectrum disorder (ASD) can be beneficial in ensuring the person receives appropriate support. People with intellectual disability often have undiagnosed co-occurring ASD, due to the specific diagnostic challenges that having intellectual disability can present. Screening tools can be useful to indicate those who are likely to require full diagnostic assessment of ASD.

Method
We conducted a systematic review of the literature. The databases ProQuest, PsycArticles, PubMed, and Web of Science were searched for articles published before July 2019. When duplicates were removed 3068 articles were retained. Articles were removed in stages and were retained if there was a possibility that the content was relevant. In total, 14 articles were reviewed fully.

Results
The articles covered eight ASD screening instruments and were reviewed in respect of the quality of the available reliability and validity data when used with people with intellectual disability.

Conclusion
A few tools have psychometric properties that indicate they have potential to screen for ASD in people with intellectual disability, but overall research with this group is limited, particularly in terms of reliability. The implications for screening and diagnosis of ASD in people with intellectual disability are discussed.