|Author, Year, Location, Reference
||Total N Enrolled in Study
||N Indicated for Diagnostic Assessment
||N Subjected to Diagnostic Assessment
||Details of Excluded Individuals
||Mean Age in Years
||Description of Inpatient Setting
||Description of Study Population
||Method of Screening
||Method of Autism Diagnosis
||Diagnostic Criteria Used
|Hare et al. (1999), England, 
||Patients on trial leave to other placements were excluded. Also, some were excluded from initial screening for administrative reasons of no clinical significance. 96% of the special hospital population was screened.
||86% (185/215) of those subjected to diagnostic assessment. Data pertaining to the male % of the 1305 individuals originally screened is not available.
||41.8 (Age range 20-77 years)
||Three secure psychiatric hospitals
||All adults. Mixture of non-ID and ID patient, though details regarding the relative proportions of each are not provided within the article.
||Autism Spectrum Disorder in Adults Screening Questionnaire (ASDASQ)1 .
||Handicaps, Behaviours and Skills (HBS) schedule  and case note analysis.
||2.4% (31/1305), increased to 4.8% (62/1305) when equivocal cases are taken into account.
|Mandell et al. (2012), USA, 
||141 (though all patients were subjected to diagnostic assessment irrespective of screening score)
||There were 348 residents within the hospital, so only 41% were screened (141/308). Researchers attempted to obtain consent from all residents; 89% of refusal were passive (i.e. patient unable to give consent). Thus, non-capacitous individuals were excluded.
||State psychiatric hospital
||Civilly committed patient. 32.6% (46/141) patients had ID. Age range not given.
||Social Responsiveness Scale (SRS) .
||Four step process: 1- Historical charts and electronic records reviewed; 2 – Diagnostic Interview for Genetics Studies (DIGS)  conducted for each patient; 3 – Autism Diagnostic Interview – Revised (ADI-R)  completed by research reliable clinicians; 4 – case conference review by two independent teams
||Overall: 9.9% (14/141). ID subgroup: 19.6% (9/46). Non-ID subgroup: 5.3% (5/95).
|Scragg and Shah (1994), England, 
||17, though 6 refused to be meet the investigator
||Female patient excluded, on basis that Asperger’s Syndrome is reporter to be much more common in males.
||No data on age of study population, though the study population were adults.
||Secure psychiatric hospital (Broadmoor, England)
||Adult males. Unclear whether any patients in the study population had ID (details on IQ are only given for 9 patients whom met criteria for AS, none of whom had an IQ consistent with ID).
||Examination of case notes
||Two stages (after initial screening stage): 1 – Screening Schedule for Autistic Behaviour (Part of the HBS interview schedule) ; 2 – Interview by the investigator.
||Gillberg and Gillberg (1989)  criteria
||1.5% (6/392) (95% CI – 0.6 to 3.3%), increased to 2.3% with the addition of equivocal cases (However, this estimate was for Asperger’s syndrome only, rather than all forms of ASD).
|Shah et al. (1982), England, 
||Exclusion of 129 patients, due to being non-mobile – ‘their inability to walk unaided limited the possibility of their showing the behaviour pattern characteristic of classic Kanner’s syndrome.’
||No data for mean age available. Youngest patients were 16 years of age.
||Long stay ID hospital3
||The entire study population had ID.
||Disability Assessment Schedule 
||Details not provided within the article.
||4% (27 to 34/761). The precise number of participants being diagnosed with ASD is not provided within the article, though they report a prevalence of 4% from a study population of 761.