Thomas 2001.

Study characteristics
Methods	Design: RCT, parallel two‐arm, single‐centre study Setting: regional hospital, Swansea, Wales, UK Recruitment: recruitment and study dates not reported Maximum follow‐up: 7 days postoperatively
Participants	231 participants undergoing elective total knee replacement surgery were randomly allocated to one of two groups: Autologous (cell salvage/intervention group): N = 115. M:F 44:71. Mean age of males 67.4 years; mean age of females 70.5 years Allogeneic (control/no cell salvage group): N = 116. M:F 55:61. Mean age of males 69.7 years; mean age of females 70.2 years Groups were comparable at baseline assessment.
Interventions	Autologous (cell salvage/intervention group): cell salvage group participants received autotransfusion of wound drainage if the volume of blood collected was > 125 mL postoperatively. The collected blood was washed and re‐suspended in saline before re‐infusion using a centrifugal cell washing machine (Haemonetics Cell Saver 5). Participants in the cell salvage group were transfused allogeneic red blood cells if their haemoglobin fell below a haemoglobin level of 9.0 g/dL after autotransfusion was completed. Allogeneic (control/no cell salvage group): control group were treated without the use of cell salvage (autotransfusion). All drainage blood was discarded.
Outcomes	Outcomes reported: number of participants transfused allogeneic blood, amount of allogeneic blood transfused, adverse events
Notes	Transfusion protocol: allogeneic blood was transfused if the haemoglobin level fell below 9.0 g/dL. Prospective registration status: the study was published prior to 2010. Ethical approval: the study was approved by the local research ethics committee. Language of publication: English Trial funding: Welsh Office for Research and Development in Health and Social Care Conflicts of interest: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method used to generate allocation sequences was not described.
Allocation concealment (selection bias)	Unclear risk	Method used to conceal treatment allocation was unclear.
Blinding of participants and personnel (performance bias) Objective outcome: mortality	Low risk	No objective outcomes reported (mortality unlikely to be affected by blinding if reported in future publications)
Blinding of participants and personnel (performance bias) Subjective: transfusion protocol	Low risk	Transfusion protocol in place: pre‐set transfusion trigger of 9 g/dL. The participants in the cell salvage group were also transfused if their haemoglobin fell below the preset trigger after autotransfusion.
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	Unclear risk	Adverse events were scrutinised in a blinded fashion to determine those possibly related to transfusion effect (wound infection, embolic events, MI, and cardiopulmonary (CP) complications). Appears to be based on the recordings taken by a research nurse ‐ no protocols described and no mention of whether the research nurse was blinded.
Blinding of outcome assessment (detection bias) Objective outcomes: mortality and transfusions	Low risk	No objective outcomes reported (mortality unlikely to be affected by blinding if reported in future publications)
Blinding of outcome assessment (detection bias) Subjective outcomes	Unclear risk	Adverse events were scrutinised in a blinded fashion to determine those possibly related to transfusion effect (wound infection, embolic events, MI, and CP complications). Appears to be based on the recordings taken by a research nurse ‐ no protocols described and no mention of whether the research nurse was blinded.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	ITT analysis
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Low risk	No baseline imbalance. Funding reported (non‐pharmaceutical)