DOMAIN 1: PATIENT SELECTION
Risk of bias: Could the selection of patients have introduced bias?
Signalling question	1. Was a consecutive or random sample of patients enrolled? ‘Yes’ if a random sample of patients with suspected psychotic symptoms were included, or consecutive patients were enrolled ‘No’ if the patients were specifically selected (not random sample) to be included in the study ‘Unclear’ if insufficient information is provided
	2. Was a case‐control design avoided? ‘Yes’ participants did not have a specific diagnosis at entry to the study even if they had psychotic symptoms ‘No’ participants had a specific diagnosis at entry to the study ‘Unclear’ if insufficient information is provided
	3. Did the study avoid inappropriate exclusions? ‘Yes’ the study explicitly states that there were no exclusions or there were no inappropriate exclusions ‘No’ some patients were inappropriately excluded e.g. if they were deemed “difficult‐to‐diagnose” patients ‘Unclear’ exclusions not explicitly reported in the study
Applicability
Signalling question	1. Are there concerns that the included patients and setting do not match the review question? ‘No’ Included patients with psychosis but not a specific diagnosis ‘Yes’ Patients already had a specific diagnosis upon entry to study (e.g. inclusion criteria lists specific diagnoses) 'Unclear' Not enough information to decide
DOMAIN 2: INDEX TEST
Risk of bias: Could the conduct or interpretation of the index test have introduced bias?
Signalling question	1. Were the index test results interpreted without knowledge of the results of the reference standard? ‘Yes’ if the index test was conducted before the reference standard, or if the person applying the index test was blinded to the results of the reference standard ‘No’ if the index test operator knew the results of the reference standard ‘Unclear’ if insufficient information is provided
	2. Did the study pre‐specify whether they were using one or multiple FRSs? ‘Yes’ if the study states the number of FRSs needed to be present to diagnose schizophrenia ‘No’ if the study does not state the number of FRSs they considered necessary to diagnose schizophrenia
Applicability
Signalling question	1. Are there concerns that the index test, its conduct, or interpretation, differ from the review question? ‘No’ if FRSs are used for diagnosing schizophrenia ‘Yes’ if the study is not using FRSs for the diagnosis of schizophrenia, e.g. the prognosis of patients, or the prevalence of FRSs ‘Unclear’ if insufficient information is provided to judge the purpose of applying FRSs
DOMAIN 3: REFERENCE STANDARD
Risk of bias: Could the reference standard, its conduct, or its interpretation have introduced bias?
Signalling question	1. Is the reference standard likely to correctly classify the target condition? ‘Yes’ if the history and clinical examination is conducted by a qualified professional (psychiatrist, nurse, social worker) ‘No’ if the history and clinical examination is conducted by insufficiently qualified individuals ‘Unclear’ if insufficient information is provided
	2. Were the reference standard results interpreted without knowledge of the results of the index test? ‘Yes’ if the reference standard was conducted before the index test, or if the person applying the reference standard was blinded to the results of the index test ‘No’ if the reference standard operator knew the results of the index test ‘Unclear’ if insufficient information is provided
Applicability
Signalling question	1. Are there concerns that the target condition as defined by the reference standard does not match the question? ‘No’ if the paper specifically looks at diagnosing schizophrenia (regardless of subtypes) ‘Yes’ if the paper also includes schizophrenia‐like illnesses ‘Unclear’ if insufficient information is provided
DOMAIN 4: FLOW AND TIMING
Risk of Bias: Could the patient flow have introduced bias?
Signalling question	1. Was there an appropriate interval between index test and reference standard? 'Yes' if reference standard and index text were applied in the same interview or within 4 weeks (applied more than once for chronic schizophrenia) 'No' if reference standard or index test were applied in different interviews beyond 4 weeks 'Unclear' if not enough information is given to assess whether there was an appropriate interval
	2. Did all patients receive a reference standard? 'Yes’ if all patients had details of history and clinical examination, with or without operational criteria ‘No’ if not all patients had a description of history and clinical examination ‘Unclear’ if insufficient information is provided
	3. Did all patients receive the same reference standard? ‘Yes’ if all patients were diagnosed with history and clinical examination; and if any operational criteria were used, the same ones were applied to all patients and all received the same clinical follow up ‘No’ if all patients received history and clinical examination but only some received operational criteria, or different operational criteria ‘Unclear’ if insufficient information is provided
	4. Were all patients included in the analysis? 'Yes' if there are no patients excluded from the analysis 'No' if there are patients excluded from the analysis 'Unclear' if not enough information is given to assess whether any patients were excluded from the analysis