Locatelli 1994.

Methods	Study design: parallel RCT Study time frame: May 1991 to November 1992 Duration of follow‐up: 1 year
Participants	Country: Italy Setting: multi‐centre Aged 18 to 70 years; RRT for at least 2 months; on dialysis for > 3 months; regular HD 3 times/week; stable clinical condition Number: treatment group 1 (50); treatment group 2 (54); treatment group 3 (51); treatment group 4 (50) Mean age ± SD (years): treatment group 1 (50.5 ± 13.5); treatment group 2 (53.7 ± 12.9); treatment group 3 (56.0 ± 12.2); treatment group 4 (52.7 ± 12.9) Sex (M): treatment group 1 (66%); treatment group 2 (72.2%); treatment group 3 (70.6%); treatment group 4 (80.0%) Exclusion criteria: presence of malignant disease; MI in the previous 12 months; stroke or TIA in the previous 6 months; severe heart failure (NYHA class 3 or 4)
Interventions	Treatment group 1 Low‐flux HD with cuprophane membranes Treatment group 2 Low‐flux HD with polysulfone membrane Treatment group 3 High‐flux HD with polysulfone membrane Treatment group 4 High‐flux HDF with polysulfone membrane Co‐interventions: not stated
Outcomes	Mortality B2 microglobulin levels Number and length of hospitalisations Kt/V
Notes	Exclusions post randomisation but pre‐intervention: not stated Stop or end point/s: not stated Additional data requested from authors: none requested Funding: the steering committee, the data coding and collection and the secretariat of this study included employees of Fresenius Medical Department, Italy
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Adequate: "Randomization was centralized at the Department of Nephrology at Lecco Hospital, using separate lists for each Center that were randomly divided into blocks of four for the assignment of two or four treatments (depending on the treatments available in the different Centers)."
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	108/205 analysed (46%) (34% due to technical reasons, acute clinical reason, fistula‐related reason, treatment inadequacy)
Selective reporting (reporting bias)	High risk	Key outcomes not reported
Other bias	High risk	Interventions not matched and patient characteristics not matched at baseline; interventions and patient characteristics not matched; commercial sponsor involved in the conduct of this study