Peralta 1999.

Study characteristics
Patient sampling	Prospective, consecutive.
Patient characteristics and setting	N included in study: 660. N in analysis: 660. Age: Range of mean ages across diagnostic groups: 28.4 to 44.9 years. Gender: M 384, F 276. Ethnicity: Not reported. Comorbid disorders: Not reported. Duration of symptoms: Not reported. Concurrent medications used: Not reported. Inclusion criteria: Symptoms at admission: delusions, hallucinations,marked formal thought disorder, gross disorganised behaviour, severe negative symptoms, or catatonic symptoms. Exclusion criteria: Demonstrable brain disorders, drug misuse confounding diagnosis, mental retardation, serious medical disease or lack of reliable external sources of information. Study aim: Examine the diagnostic significance of FRSs for schizophrenia. Previous treatment for schizophrenia: Not reported. Clinical setting: Inpatients. Country: Spain.
Index tests	Description of FRS used: First‐rank symptoms were assessed by the authors through the Manual for the Assessment of Schizophrenia (MAS) interview assessing 12 FRS's, including "made feelings" symptoms. FRS rated with SAPS ( Scale for the Assessment of Positive Symptoms, 1984). Professionals performing test: Two authors, doctors in the psychiatric unit. Resolution of discrepancies: Not reported. How FRS used in study: Diagnosis.
Target condition and reference standard(s)	Reference standard: Three sets of reference criteria were used: DSM‐III‐R narrow concept (i.e. DSM‐III‐R schizophrenia), a DSM‐III‐R broad concept (i.e. schizophrenia, schizophreniform disorder and schizoaffective disorder) and the Feighner* criteria for definite schizophrenia (Feighner et al, 1972). Target condition(s): Schizophrenia, schizophreniform disorder, schizoaffective disorder, mood disorder, delusional disorder, brief reactive psychosis, atypical psychosis. Professionals performing test: Two authors, doctors in the psychiatric unit.. Resolution of discrepancies: Consensus diagnoses were made by two authors after reviewing all the available information. Inter‐rater reliability for DSM‐111‐R and Feighner schizophrenia was 0.88 and 0.76, respectively.
Flow and timing	Study process: Diagnoses were made using the reference standards at the end of the index admission. FRS assessed in clinical interviews conducted within the first five days of admission. Follow‐up: Not reported. Exclusions: Not explicitly reported. All patients included in the analysis.
Comparative
Notes	Part of the Pamplona Study on the phenomenology of functional psychotic disorders. *Feighner's definition was used as the 'gold standard' because it does not give particular diagnostic emphasis to FRSs
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	Low
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?	Yes
		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	Low
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Yes
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