Wizemann 2000.

Methods	Study design: parallel RCT Study time frame: not stated Duration of follow‐up: 48 months
Participants	Country: Germany Setting: single centre Chronic HD patients on dialysis with low‐flux HD for at least 3 months Number: treatment group (23); control group (21) Mean age ± SD (years): treatment group (61 ± 12); control group (60 ± 11) Sex (M/F): treatment group (12/11); control group (13/8) Exclusion criteria: not stated
Interventions	Treatment group HDF with high‐flux polysulfone (Fresenius F‐80S) membranes for 24 months QD: 100 to 200 mL/min Duration of each dialysis session: 4.5 hours Total substitution fluid volume was targeted to 60 L/session Control group HD with low‐flux polysulfone (Fresenius F8) membranes for 24 months QB: 400 to 500 mL/min QD: 500 mL/min Dialysis duration: 4.5 hours Co‐interventions: not stated
Outcomes	B2 microglobulin reduction ratio URR
Notes	Exclusions post randomisation but pre‐intervention: not stated Stop or end point/s: not stated Additional data requested from authors: method of randomisation; details regarding blinding; raw data for B2 microglobulin values Funding: sponsor involved in authorship and/or data management
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not stated
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	High risk	18% loss to follow‐up
Selective reporting (reporting bias)	High risk	Study protocol unavailable and outcomes of interest reported incompletely, cannot be used in meta‐analysis (e.g. BP)
Other bias	High risk	Sponsor involved in authorship and/or data management; interventions not matched

ACEi ‐ angiotensin‐converting enzyme inhibitor; AFB ‐ acetate‐free biofiltration; BD ‐ conventional bicarbonate dialysis; BP ‐ blood pressure; CKD ‐ chronic kidney disease; CrCl ‐ creatinine clearance; CV ‐ cardiovascular; EPO ‐ erythropoietin; ESKD ‐ end‐stage kidney disease; Hb ‐ haemoglobin; HCT ‐ haematocrit; HD ‐ haemodialysis; HF ‐ haemofiltration; HDF ‐ haemodiafiltration; HTN ‐ hypertension; LVMi ‐ left ventricular mass index; MAP ‐ mean arterial pressure; MI ‐ myocardial infarction; QB ‐ blood flow rate; QD ‐ dialysate flow rate; QoL ‐ quality of life; rHuEPO: recombinant human EPO; RRT ‐ renal replacement therapy; TIA ‐ transient Ischaemic attack; URR ‐ urea reduction ratio