Heikkilä 1992.

Methods	Randomisation: “randomised”. Blinding: double‐blind. Duration: 8 weeks. Design: parallel. Location: four Finnish mental hospitals (multicentre). Setting: inpatients.
Participants	Diagnosis (38 completers of at least 4 weeks): chronic schizophrenia (N = 34), paranoid states (N = 2), reactive paranoid psychosis (N = 2). N = 49. Gender: 19M, 19F. Age: mean 36 years. 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: flexible dose, dose range: 2 mg to 30 mg/day, mean dose: 10.3 mg/day. N = 23. 2. Zuclopenthixol: flexible dose, dose range: 10 mg to 75 mg/day, mean dose: 33.5 mg/day. N = 26. “The doses were chosen on the basis of the condition of the patients.” “According to the protocol, the doses should be individually adjusted according to the patient´s response to treatment.” Rescue medication: “Biperiden could be prescribed in case of extrapyramidal side‐effects and nitrazepam or chloral hydrate could be given as a hypnotic.”
Outcomes	Examined: Clinically important response to treatment: “a slightly modified version of the Clinical Global Impressions Scale (CGI)”. Mental state general: 16‐item Brief Psychiatric Rating Scale (BPRS). Leaving the study early due to any reason. Adverse effects: use of antiparkinson medication. Unable to use: Global state general: CGI (modified version). Adverse effects: UKU Side‐Effekt Rating Scale (no information regarding the occurrence of adverse effects over the whole trial duration).
Notes	Study participants were 49 participants “with acute psychotic states” (38 completers of at least 4 weeks drug treatment). Criteria for study inclusion were “diagnosis of acute schizophrenia or an exacerbation of chronic schizophrenia, paranoid states or reactive paranoid psychosis” and a 16‐item BPRS total score >25. “All patients treated for at least 4 weeks were included in the statistical analyses of the results.”
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	“Randomised”. No further details.
Allocation concealment (selection bias)	Unclear risk	No further details.
Blinding (performance bias and detection bias) (performance bias)	Low risk	“Double‐blind”. “tablets of identical appearance”
Blinding (performance bias and detection bias) (detection bias)	Unclear risk	“Double‐blind”. No further details.
Incomplete outcome data (attrition bias) All outcomes	High risk	The overall‐attrition was high: 38 of 49 participants (77.6%) left the trial early. The trial authors indicated that 18 of 23 participants (78.3%) in the haloperidol‐group and 20 of 26 participants (76.9%) in the zuclopenthixol‐group discontinued the drug treatment prematurely.
Selective reporting (reporting bias)	Unclear risk	The reported adverse effects data were not usable for this systematic review.
Other bias	Unclear risk	Insufficient information to assess whether an important risk of bias exists.