Table 1 Inclusion and Exclusion Criteria

Inclusion Criteria

 Documents with guidance-based status for HCPs working in secondary care in the UK; or were published papers, aimed at HCPs, with the aim of reviewing CPGs

 Documents related to autism diagnosis and assessment for either children, adults or both

 Documents produced either by or through government or professional clinical bodies or published in a journal aimed at HCPs

 Documents related to diagnosis and assessment in UK (England, Scotland, Wales and N Ireland)

 Documents dated from 2009 (reflecting publication of the first UK specific Autism Act) or were the most recent CPG published by a key professional body

Exclusion Criteria

 Documents related solely to referral, treatment, prognosis or support services

 Reviews of diagnostic criteria and other academic papers

 Guidelines related to primary care as we were interested in diagnosis rather than referral

 Narrative reviews, editorials and opinions

 Documents related to parliament or legislature; national or regional strategies as they are not the primary source for clinicians

 Local guidance

 Guidance provided by private providers of diagnostic services

 International professional body guidelines (other than ICD/DSM)