Radhakrishnan 1983.

Study characteristics
Patient sampling	Prospecitve, consecutive.
Patient characteristics and setting	N included in study: 266. N in analysis: 266. Age: Not reported. Gender: Not reported. Ethnicity: Not reported. Comorbid disorders: Not reported. Duration of symptoms: Not reported. Concurrent medications used: Not reported. Inclusion criteria: All admissions over a period of 18 months. Exclusion criteria: Not reported. Study aim: To evaluate the prevalence of FRS and their diagnostic and prognostic implications. Previous treatment for schizophrenia: Not reported. Clinical setting: Inpatients. Country: India.
Index tests	Description of FRS used: Questions to establish the presence of FRS were asked according to the standardised interview schedule of the International Pilot Study of Schizophrenia. The patients were interviewed before starting on any medication. The first rank symptoms were rated as either present, or absent. Professionals performing test: Not reported. Resolution of discrepancies: Not reported. How FRS used in study: Prevalence, diagnosis, prognosis.
Target condition and reference standard(s)	Reference standard: Diagnostic criteria used were according to the International Classification of Diseases: lCD 9. Only those patients who satisfied the criteria of Feighner for schizophrenia were included in the schizophrenia group. Target condition(s): Schizophrenia, affective disorders, hysterical psychosis, paranoid state, acute psychotic reaction, organic psychosis, neurotic disorders, personality disorders, and temporal lobe epilepsy. Professionals performing test: Not reported. Resolution of discrepancies: Not reported.
Flow and timing	Study process: Not reported when patients were diagnosed and interviewed for FRS. Follow‐up: Not reported. Exclusion: Exclusions not explicitly reported. All participants received a diagnosis according to the reference standard, unclear whether all were evaluated for FRS.
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?	Yes
Was a case‐control design avoided?	Unclear
Did the study avoid inappropriate exclusions?	Unclear
		Unclear	High
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
		Unclear	Low
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
		Unclear	Unclear
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?	Yes
Did all patients receive the same reference standard?	Yes
Did all patients receive an index test?	Yes
Did all patients receive the same index test?	Yes
		Low