Cai 2008.

Methods	Allocation: parallel, randomised Blind: not stated Setting: hospital (inpatient), single centre Country: China Length of study: 8 weeks
Participants	Diagnosis: treatment‐resistant schizophrenia (CCMD‐3) Total N at randomisation = 100 Sex: male 57, female 43 Age (years): range 18 to 60 Length of illness (years): range 1 to 10 History: BPRS score > 50; received at least 3 types of resistance psychiatric drug therapy, of which at least 2 different classes of chemical structures; dose of each drug equivalent to chlorpromazine 600 mg/d or more, failure after more than 4 weeks of treatment, or failure after 4 weeks of treatment when receiving clozapine (≥ 450 mg/d) ('failure' was defined as the reduction rate of BPRS score ≤ 20%). Exclusion criteria: people with severe heart, liver, kidney disease, chronic body diseases, epilepsy, alcohol or drug abusers, MECT contraindications.
Interventions	ECT group (n = 50): MECT + clozapine Content: participants who received clozapine before enrolment continued to use clozapine. Participants who received other antipsychotics before enrolment needed a 1‐week wash‐out period and then received clozapine. The initial dose of clozapine was 50 mg/d, increased to 50 to 100 mg/d alternate days. The maximum dose of clozapine was no more than 300 mg/d when combined with MECT. Frequency: 3 times a week for MECT, not stated for clozapine Course of treatment (MECT): 6 to 12 sessions Treatment duration: 8 weeks Control group (n = 50): Clozapine alone Content: the usage and dosage of clozapine was same as above. The maximum dose ranged from 300 mg/d to 700 mg/d. Frequency: not stated Treatment duration: 8 weeks
Outcomes	Response to treatment: clinically significant response to treatment* Mental state: assessed by BPRS Adverse events: assessed by TESS
Notes	*Clinically significant response assessed by the reducing score rate of BPRS: 1) cure: reducing rate ≥ 75%; 2) significant improvement: reducing rate between 50% and 74%; 3) improvement: reducing rate between 25% and 49%; 4) no clinical response: reducing rate < 25%. Clinically significant response to treatment was defined as cure + significant improvement. Contact information: Third People's Hospital of Yuebei, Lechang, Guangdong, China
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "...were divided randomly into two groups..." (p.1423) Comments: The author described a random component in the sequence generation process, but no details were provided on randomisation method.
Allocation concealment (selection bias)	Unclear risk	Comments: The author did not describe the allocation concealment. Insufficient information to permit judgement of 'low risk' or 'high risk'.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Comments: Participants and personnel could not be blinded as 1 group did not use ECT, and no sham‐ECT was used.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comments: The author did not describe the blinding of outcome assessment. Insufficient information to permit judgement of 'low risk' or 'high risk'.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comments: No missing outcome data.
Selective reporting (reporting bias)	Low risk	Comments: The protocol is not available; all outcomes stated in methods were reported in results.
Other bias	Low risk	None obvious.