Various drugs 1962b.

Study characteristics
Methods	Randomisation: randomised, no further details. Allocation: psychiatrist without contact to the participants held the key and filled the medication containers. Blinding: double‐blind, exact placebo replicas. Duration: ~ 43 weeks. Design: parallel. Location: single‐centre. Setting: outpatient.
Participants	Diagnosis: schizophrenia without positive symptoms (clinical diagnosis). N = 43. Gender: 16 men, 27 women. Age: typically 40 to 50 years. History: duration stable‐ out of hospital for at least a year (typically 2 to 4 years), duration ill‐ n.i., number of previous hospitalisations‐ typically 2‐3, age at onset n.i., severity of illness n.i., but no positive symptoms at baseline, baseline antipsychotic dose‐ maximum 300 mg chlorpromazine per day.
Interventions	1. Drug: various phenothiazines, mainly chlorpromazine. Fixed/flexible dose: flexible. Allowed dose range: not limited, but complete discontinuation was not allowed. Mean dose: 150 mg/day to 200 mg/day chlorpromazine. N = 24. 2. Placebo: duration of taper: 0 days. N = 19. Rescue medication: not allowed.
Outcomes	Examined Relapse: clinical judgement. Service use: number of participants rehospitalised.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomised, no further details.
Allocation concealment (selection bias)	Low risk	Psychiatrist without contact to the participants held the key and filled the medication containers.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Double‐blind, exact placebo replicas.
Blinding (performance bias and detection bias) Subjective outcomes	Unclear risk	Double‐blind, exact placebo replicas.
Blinding (performance bias and detection bias) Objective outcomes	Low risk	Double‐blind, exact placebo replicas.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Unclear ‐ whether participants discontinued the study prematurely was not reported.
Selective reporting (reporting bias)	Low risk	No evidence for selective reporting.
Other bias	High risk	Some placebo participants continued to take medication, study terminated early.