Kurihara 1983.

Methods	Randomisation: “assigned at random”. Blinding: double‐blind. Duration: 8 weeks. Design: parallel (three‐arm study also investigating clocapramin). Location: “multi‐clinic” (42 institutes). Setting: “mainly inpatients”.
Participants	Diagnosis: schizophrenia. N = 189. Gender: 105M, 84F. Age: "most of the participants were between 30 and 49 years", no further details available. History: duration stable: not indicated, duration of illness: not indicated, number of previous hospitalisations: not indicated, age at onset: not indicated, severity of illness: not indicated, baseline antipsychotic dose: not indicated.
Interventions	1. Haloperidol: “fixed‐flexible method”, dose range: 3 mg to 12 mg/day, mean dose: not indicated. N = 94. 2. Perphenazine: “fixed‐flexible method”, dose range: 9 mg to 36 mg/day, mean dose: not indicated. N = 95.    Rescue medication: anti‐Parkinsonian and hypnotics were allowed.
Outcomes	Examined: Adverse effects: akathisia, dyskinesia, dystonia. Unable to use: Global state general: Global improvement rating (no raw data available). Mental state general: Keio University Psychiatric Symptoms Rating Scale (no raw data available).
Notes	“The patients were relatively fresh cases with the clinical state of deficiency of initiative, blunted affect, hallucinations and delusions”.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	“Patients were assigned at random to the clocapramine, perphenazine and the haloperidol group”. No further details.
Allocation concealment (selection bias)	Unclear risk	No further details.
Blinding (performance bias and detection bias) (performance bias)	Low risk	“Double‐blind”. “Both drugs were confirmed as being indistinguishable from each other, having an identical appearance, and identical colour shades and weights.”
Blinding (performance bias and detection bias) (detection bias)	Unclear risk	“Double‐blind”. No further details.
Incomplete outcome data (attrition bias) All outcomes	Low risk	There were 32 patients who left the study early, but all data of the 286 randomised participants were used.
Selective reporting (reporting bias)	High risk	The number of participants randomised to each treatment group (haloperidol, clocapramine, or perphenazine) was not indicated. These data were only available for the completers of the trial. The outcome data were not fully addressed (no raw data for the Global improvement rating and the Keio University Psychiatric Symptoms Rating Scale). No information regarding the number of participants that received a medication with antiparkinson drugs.
Other bias	Unclear risk	Insufficient information to assess whether an important risk of bias exists.