Katafuchi 2003.

Methods	Study design: parallel, 2‐arm RCT Time frame: July 1991 to September 1995 Duration of follow‐up: 60 months
Participants	Setting: single centre Country: Japan Inclusion criteria: biopsy‐proven IgAN; aged < 60 years; SCr ≤ 1.5 mg/dL Number (analysed/randomised): treatment group (43/49); control group (47/54) Mean age ± SD (years): treatment group (33.6 ± 13.4); control group (32.5 ± 10.8) Sex (M/F): treatment group (15/28); control group (22/25) Exclusion criteria: previous treatment with steroids; pregnancy; HPS; SLE; DM; neoplasia; active peptic ulcer disease; viral hepatitis; other infection
Interventions	Treatment group Prednisolone: 20 mg/day for 1 month, 15 mg/day for 1 month, 10 mg/day for 1 month, 7.5 mg/day for 3 months, 5 mg/day for 18 months Dipyridamole: 150 or 300 mg/day Control group Dipyridamole: 150 or 300 mg/day Co‐interventions Not reported
Outcomes	ESKD Urinary protein excretion SCr CrCl
Notes	Funding: not reported Trials registration identification number: not applicable
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information to permit judgement
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement
Blinding of participants and personnel (performance bias) All outcomes	High risk	Open‐label study
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinding of outcome assessment not specifically reported. Key outcomes were objective laboratory measures and were unlikely to be affected by any knowledge of treatment allocation
Incomplete outcome data (attrition bias) All outcomes	High risk	6/49 participants lost to follow up in intervention group; 7/54 participants lost to follow up in control group
Selective reporting (reporting bias)	High risk	There was no pre‐specified protocol identified for this study. The study did not report extractable data for the key outcomes that would be expected for a study of this type (e.g., death (any cause), malignancy, infection)
Other bias	Low risk	The study appears to be free of other sources of bias