Chandrasena 1987.

Study characteristics
Patient sampling	Sri Lanka: prospective and randomly selected. UK and Canada: unclear how patients were sampled.
Patient characteristics and setting	N with a clinical diagnosis of psychosis: 741. N screened: 741. Age: Not reported. Gender: Not reported. Ethnicity: Sri Lanka: (n = not reported). UK and Canada: Afro‐Craibbean immigrants n = 60, Asian immigrants n = 60, "Native" n = 64. Comorbid disorders: Not reported. Duration of symptoms: Not reported. Concurrent medications used: not reported. Inclusion criteria: "Schizophrenics and non‐schizophrenics", no further details reported. Sri Lanka: all had “Functional Psychosis” as defined by the World Health Organization for the IPSS. Exclusion criteria: Not reported. Study aim: To investigate whether the prevalence of some individual FRS also vary with ethnicity and nationality. Previous treatment for schizophrenia: Not reported. Clinical setting: Inpatients. Country: Sri Lanka, UK, and Canada.
Index tests	Description of FRS used: FRSs were recorded using a modified version of the Present State Examination (PSE; translated standardised 9th version, modified to elicit and record all eleven FRS, since PSE reliably elicits only seven FRS). Professionals performing test: Not reported. Resolution of discrepancies: Not reported. How FRS used in study: Prevalance.
Target condition and reference standard(s)	Reference standard: Sri Lankan: the World Health Organization definitions for the IPSS. UK and Canada: ICD‐9. Target condition(s): Schizophrenia and non‐schizophrenia. Professionals performing test: Not reported. Resolution of discrepancies: Not reported.
Flow and timing	Study process: Not reported. Follow‐up: Study carried out over 12 years. Exclusions: No exclusions reported. All participants included on the 2 x 2 tables.
Comparative
Notes
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Unclear
		Unclear	Unclear
DOMAIN 2: Index Test All tests
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
Did the study pre‐specify whether they were using one or multiple FRSs?	No
		High	High
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
		Unclear	Low
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Were all patients included in the analysis?	Yes
Did all patients receive a reference standard?	Unclear
Did all patients receive the same reference standard?	Unclear
Did all patients receive an index test?	Yes
Did all patients receive the same index test?	Yes
		Unclear