Koshikawa 1993.

Study characteristics
Methods	Study design: parallel RCT Study duration: April 1989 to June 1992 Duration of follow‐up: 24 weeks
Participants	Setting: not reported Country: Japan Inclusion criteria: biopsy‐proven IMN with steroid‐resistant nephrotic syndrome Baseline characteristics Pathology stage: not reported GFR: ≥ 50 mL/min Baseline declining kidney function: not reported Previous immunosuppressive status: receiving a daily maintenance dose of 20 mg prednisolone‐equivalent a day (including zero dosage) before entry was allowed. Other immunosuppressant medication should be stopped at the start of the study Number: treatment group (48); control group (41) Age: > 15 years Sex (M/F): not reported Exclusion criteria: not reported
Interventions	Treatment group Mizoribine: 50 mg 3 times/day after meals for 24 weeks Control group Placebo Co‐interventions Use of ACEi or ARB during follow‐up: not reported
Outcomes	50% or 100% SCr increase Partial or complete remission Side effects leading to patient withdrawal or hospitalisation
Notes	Funding information: not reported Published in Japanese
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information about the sequence generation process to permit judgement
Allocation concealment (selection bias)	Unclear risk	No sufficient detail about concealment of the random allocation sequence before or during enrolment of participants
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind; no information on blinding of outcome‐assessors provided
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information to permit judgement
Incomplete outcome data (attrition bias) All outcomes	Low risk	Only 2/48 patients in the treatment group did not complete 24‐week follow‐up
Selective reporting (reporting bias)	High risk	The primary outcome such as death and ESKD were not reported
Other bias	High risk	The data were abstracted from a RCT aiming to investigate the effect of mizoribine on steroid‐resistant primary nephrotic syndrome. This study included all different pathologic variants of nephrotic syndrome. The randomisation was not stratified according to the pathologic diagnosis