Cheng 2005.

Study characteristics
Methods	Design: RCT, parallel two‐arm, single‐centre study Setting: District General Hospital, Hong Kong Recruitment: June 2002 to May 2004 Maximum follow‐up: 3 days postoperatively
Participants	60 participants undergoing unilateral total knee arthroplasty (TKA) were randomly allocated to one of two groups: Group 1 (Cell salvage/intervention group): N = 26. M:F 6:20. Mean (range) age 72 (57 to 84) Group 2 (Control/no cell salvage group): N = 34. M:F 12:22. Mean (range) age 69.4 (55 to 78) There were no differences between groups at baseline.
Interventions	Group 1: cell salvage group (DONOR system) had their blood reinfused from drains using a 40 µm blood filter between the collection bag and the intravenous site within 6 hours of surgery. All participants had their drains removed on postoperative day 2 or 3. The DONOR system is an integrated, closed system designed for the collection and reinfusion of drained wound blood. It consists of an 800 mL chlorine‐free, pre‐evacuated collection vessel, a vacuum regulator, and a 40 µm integrated filter for salvaged blood. Group 2: control group received no postoperative autotransfusion.
Outcomes	Outcomes reported: amount of allogeneic blood transfused, number of participants transfused allogeneic blood, febrile complications, adverse events, blood loss
Notes	Transfusion protocol: allogeneic blood transfusion was given if the haemoglobin level was < 9.0 g/dL, or on the authority of the lead physician if the participant experienced severe anaemic symptoms. Transfusions were given according to the following criteria: Hb 81‐90 g/L = 1 unit Hb 71‐80 g/L = 2 units Hb 61‐70 g/L = 3 units Hb 50‐60 g/L = 4 units Prospective registration status: the study was published prior to 2010. Ethical approval: the study was approved by the ethics board of the Hong Kong Hospital's Authority Kowloon West Cluster. Language of publication: English Trial funding: Tung Wah Group of Hospitals Research Fund Conflicts of interest: none reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Allocated into a reinfusion group and a control group. Randomisation was by sealed opaque envelopes, which were well mixed by independent personnel and consecutively assigned a case number from 1 to 60.
Allocation concealment (selection bias)	Low risk	Randomisation was by sealed opaque envelopes, which were well mixed by independent personnel and consecutively assigned a case number from 1 to 60
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	High risk	Transfusion protocol based on Hb level, or on the authority of the lead physician if the participant experienced severe anaemic symptoms. Group allocation revealed at end of procedure. Transfusion decisions made in unblinded fashion.
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	Low risk	Near the end of each operation, the corresponding envelope was opened, and the surgeon was informed at the time of drain insertion to achieve a single‐blind effect.
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	Low risk	Described as single blind only (outcome assessors unblinded), though all outcomes deemed low risk of bias
Incomplete outcome data (attrition bias) All outcomes	Low risk	States 60 participants were enroled, and both pre‐op and post‐op data suggest 60 participants (26 and 34) analysed. No other info regarding patient flow. One participant mentioned in reinfusion group (blood discarded), does not appear to have been excluded
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Low risk	Funding reported (non pharma). No apparent baseline imbalance