Sklar 1998.

Study characteristics
Methods	Study design Cross‐over RCT Study dates Duration of follow‐up: 1 week Time frame: not reported
Participants	Study characteristics Setting: multicentre (Department of Medicine, United Health Services Hospitals, Binghamton; State University of New York, Health Science Center at Syracuse, Syracuse, NY; and the Guthrie Research Institute, Sayre, PA) Country: USA Inclusion criteria: patients receiving maintenance HD treatments affected by post‐dialysis fatigue Exclusion criteria: not reported Baseline characteristics Number (analysed/randomised): intervention group 1 (8/not reported); intervention group 2 (8/not reported) Mean age ± SD (years): overall (61 ± 12) Sex (M/F): overall (9/7) Dialysis type: HD Dialysis vintage (years) (mean ± SD): not reported Comorbidities CVD: not reported Diabetes: not reported Hypertension: not reported Depression (clinician diagnosis): not reported
Interventions	Intervention classification Pharmacological intervention Indication: study targeting fatigue Intervention group 1 Cuprophan low flux dialyser membranes Intervention group 2 Polymethylmethacrylate low‐flux dialyser membranes Co‐interventions Each patient was dialysed 3 times/week on a Baxter SPS 550 machine
Outcomes	Outcomes reported Fatigue outcome measures used: validation data available TNF alfa (pre and post‐dialysis): assessed during the first and last dialysis treatments Change in the body weight (pre and post‐dialysis): assessed during the first and last dialysis treatments SBP (pre and post‐dialysis): assessed during the first and last dialysis treatments Change in osmolarity (pre and post‐dialysis): assessed during the first and last dialysis treatments Fatigue score 6‐hour logs of sleep (fatigue scores were calculated as the sum of the hours of sleep and the hours of fatigue experienced by patients for up to 6 hours after each dialysis treatment): assessed until the end of treatment Fatigue index questionnaire (each domain rated from 1 to 5): assessed during the first and last dialysis treatments Intensity Duration Frequency
Notes	Additional information Funding: Donald Guthrie Foundation for Research and Education, Sayre, PA, and the Arthur T. Cantwell Foundation, Coudersport, PA Conflicts of interest/disclosures: not reported Trial registration identification number: not applicable A priori published protocol: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Sequence generation methods were not reported in sufficient detail to permit judgement
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment was not reported in sufficient detail to permit judgement
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote: "Patients were blinded with respect to the type of membrane used during all dialysis treatments throughout the study." Comment: Not reported if investigators were blind. However, interventions were different and investigators could be aware of the treatment assigned
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "Levels of post dialysis fatigue were determined by analysis of 6‐hour logs of sleep and perception of fatigue recorded by patients after each of these dialysis treatments. At the completion of the study, the patients submitted their log sheets to one of the investigators." Comment: The outcomes were assessed with an appropriate measure, without differences between groups. However, subjective measures were used, it was not stated whether outcomes were assessed without knowledge of treatment allocation, and knowledge of treatment assignment may have influenced reporting. Participant beliefs about the superiority/inferiority of either intervention could have influenced their assessment of the outcome, but there was no evidence that this was likely. Other objective outcomes were assessed
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote: "Five patients were not included in the data analysis because they were individuals who destabilized medically (2) or submitted incomplete log sheets (3)." Comment: Overall, 16/21 participants completed the study (> 5% lost to follow‐up, difference between groups could not be assessed). Reasons for discontinuations seemed to be not related to the treatment allocation
Selective reporting (reporting bias)	High risk	Information about the protocol and the statistical analysis plan were not reported. It was not reported if multiple eligible outcome measurements (scales and time points) were pre‐specified. It was unclear if the reported approach to analysing this outcome was pre‐specified or influenced by the results. Fatigue at the end of treatment was not reported in a format that was extractable for meta‐analysis (cross‐over study: data related to the first period were not clearly reported). All outcomes that should be addressed (fatigue, cardiovascular disease, and death) were not reported
Other bias	Unclear risk	Baseline characteristics between groups were not reported. Funding was unlikely to influence the data analysis and conflicts of interest were not reported