Ihle 1989.

Methods	Study design: parallel RCT Duration of study: not reported Study follow‐up period: 18 months
Participants	Country: Australia Setting: single centre, outpatient department Patients with stable SCr 350 to 1000 µmol/L for 3 months before enrolment; CKD stage: 4‐5 Number (randomised/analysed): very low protein diet group (34/31); normal protein diet group (38/33) Mean age ± SD (years): very low protein diet group (37.2. ± 5.7); normal protein diet group (36.8 ± 4.8) Sex (M/F): very low protein diet group (22/9); normal protein diet group (21/12) Exclusion criteria: potentially reversible kidney dysfunction; systemic disease (diabetes, connective tissue disorders); medications that could alter course of disease (immunosuppressive agents, ACEi)
Interventions	Very low protein diet group Prescribed protein intake: 0.4 g protein/kg/d Normal protein diet group Prescribed protein intake: > 0.75 g/kg/d Both groups received 35 to 40 kcal/kg/d Co‐interventions Not reported
Outcomes	ESKD: SCr > 1300 µmol/L or uraemic symptoms requiring dialysis Decline in GFR over time (measured by Cr‐51 EDTA clearance) Body weight
Notes	Three participants withdrew voluntarily; 5 excluded for not complying with medication or dietary regimen Data from 64 evaluated participants included Funding source: not reported
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	Not blinded and lack of blinding may influence patient management
Blinding of outcome assessment (detection bias): End or change in GFR End of change in GFR	Low risk	Primary outcome was laboratory measurement of GFR by EDTA clearance and unlikely to be influenced by lack of blinding
Blinding of outcome assessment (detection bias): Need to start dialysis Need to start dialysis	High risk	Decision to commence dialysis depending on uraemic symptoms and/or SCr > 1300 µmol/L
Incomplete outcome data (attrition bias) All outcomes	High risk	8/72 (11%) excluded from analyses (3 withdrew; 5 excluded for non‐compliance with diet)
Selective reporting (reporting bias)	High risk	Report on number reaching ESKD & GFR. Body weight only reported graphically. Deaths not reported but there appear to be no deaths
Other bias	Unclear risk	Insufficient information to permit judgement