B +ziprasidone 2014.

Methods	Allocation: randomised. Blinding: double‐blind. Duration: 16 weeks. Setting: outpatients. Design: parallel. Country: Italy.
Participants	Diagnosis: schizophrenia (DSM‐IV). N = 40. Sex: M 13, F 27. Age: ˜ 35 years. History: chronic, treatment resistant patients that demonstrated persistent positive and negative symptoms despite an adequate trial of clozapine.
Interventions	Combination: clozapine (350 mg to 600 mg/day) + ziprasidone (80 mg/day) (N = 20). Monotherapy: clozapine (350 mg to 600 mg/day) + placebo (N = 20).
Outcomes	‐ Usable data ‐ Leaving the study early. Mental State: PANSS (Total), BPRS. Adverse event: requiring discontinuation. ‐ Not able to use ‐ Mental state: PANSS (Positive, Negative) (Skewed data). Adverse event: white blood cell count (No data reported). ‐ Not used in this review ‐ CDSS (Calgary Depression Scale for Schizophrenia).
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	“Prerandomized codes generated by computer.”
Allocation concealment (selection bias)	Low risk	“Coded treatments were allocated sequentially to subjects in order of their registration for the trial. The randomization list was held securely.”
Blinding (performance bias and detection bias) All outcomes	Unclear risk	“None of the research personnel, who enrolled, assessed, and treated the patients, were aware of the patient assignments until the study was concluded. Ziprasidone and placebo were dispensed in identical‐appearing capsules; patients randomized to placebo took the same number of capsules as those assigned to ziprasidone.”
Incomplete outcome data (attrition bias) All outcomes	High risk	“Two discontinuations in the ziprasidone group were all attributed to treatment‐emergent adverse events (akathisia and sedation) and 2 withdrew for perceived lack of efficacy. Among a total of 3 dropouts in the placebo group, 2 were due to non‐compliance with the visits and 1 withdrew due to a subjectively assessed lack of efficacy.” The reasons for leaving the study early differ across groups. “An intention‐to‐treat analysis with last‐observation‐carried forward was performed.”
Selective reporting (reporting bias)	High risk	No protocol available. “No clinically significant changes” reported for haematological parameters.
Other bias	Low risk	None obvious.