ISKDC 1974.

Methods	Study design: parallel RCT Time frame: April 1970 to June 1972 Follow‐up period: 24 months
Participants	Setting: tertiary, multicentre Countries: Europe, USA, Mexico, Hong Kong, Japan SRNS: failure to achieve remission (proteinuria ≤ 4 mL/m2/h) after 8 weeks of prednisone (60 mg/m2/d for 4 weeks then 40 mg/m2/d for 3 consecutive days out of 7); aged 12 weeks to 16 years at onset of nephrotic syndrome; all had initial steroid resistance Number: CPA‐prednisone group (18); prednisone group (13; 2 patients with MNS excluded) Age: not reported Sex (M/F): not reported Histology CPA‐prednisone group: MCD (7); FSGS (7); MesPGN (2); diffuse proliferative GN (2) Prednisone group: MCNS (7); FSGS (3); diffuse proliferative GN (1); unknown (2) Exclusion criteria: not reported
Interventions	CPA‐prednisone group Oral CPA 5 mg/kg/d till WCC < 5000 then 1 to 3 mg/kg/d Intermittent prednisone for 90 days Prednisone group Intermittent prednisone for 90 days Co‐interventions Not reported
Outcomes	Complete remission: proteinuria ≤ 4 mg/m2/h for 3 consecutive days at about 3 to 4 months but unclear Partial remission
Notes	Exclusions post randomisation but pre‐intervention: none reported Stop or end points/s: not reported Additional data requested from authors: none
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Study described as randomised; method of randomisation not reported
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding of participants/investigators; lack of blinding could influence management
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Outcome assessment by quantitative measurement of protein on overnight urine collection or semi‐quantitative based on urinalysis Unclear how many patients had laboratory assessment of outcome
Incomplete outcome data (attrition bias) All outcomes	Low risk	All patients followed up
Selective reporting (reporting bias)	High risk	Complete and partial remission reported but no definition for partial remission provided; adverse effects not reported specifically for steroid‐resistant patients
Other bias	Low risk	Support from NIH AM 14490‐93, National Kidney Foundation, Kidney Foundation of New York, John Rath Foundation