Dramis 2006.

Study characteristics
Methods	Design: RCT, parallel two‐arm design Setting: speciality orthopaedic hospital, Birmingham, West Midlands, UK Recruitment: consecutive 30‐day period, dates not specified Maximum follow‐up: 4 days postoperatively
Participants	49 participants undergoing primary unilateral total knee arthroplasty were randomly allocated to one of two groups: Group A (Cell salvage/intervention group): N = 32. M:F 11:21. Mean (range) age 69 (49 to 83) Group B (Control/no cell salvage group): N = 17. M:F 4:13. Mean (range) age 72 (62 to 91) There was no difference in preoperative haemoglobin concentrations between groups.
Interventions	Group A (Cell salvage/intervention): cell salvage group (CellTrans system) had their drained blood filtered through a 40 µm filter before being reinfused. Before closure of the wound, two drainage tubes were inserted. The tubes were connected through a Y‐connector to the CellTrans assembly which contains two transfusion bags. The clamps remained closed for 20 minutes after the wound had been closed off. The drainage was started in the recovery room and collected for 6 hours or until 600 mL of blood had accumulated at which point reinfusion took place. Collection up to a maximum of 12 hours ‐ thereafter the blood collected in the drains was discarded. Group B (Control/no cell salvage group): control group received a standard vacuum drain (Redivac high vacuum drainage system). Drains were removed routinely at 48 hours. Contents were discarded.
Outcomes	Outcomes reported: number of participants transfused allogeneic blood, amount of allogeneic blood transfused, Hb levels, cost
Notes	Transfusion protocol: the trigger for transfusing allogeneic blood was a postoperative haemoglobin level of < 9.0 g/dL or clinical symptoms of anaemia. Prospective registration status: the study was published prior to 2010. Ethical approval: it is not clear whether the study was approved by an ethics committee or instructional review board. Language of publication: English Trial funding: not reported 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: "The trigger for transfusing allogeneic blood was a postoperative Hb of < 9.0 g/dL or clinical symptoms of anaemia."
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	Low risk	No info on blinding ‐ may impact clinical decision‐making but not for our outcomes (low risk related to transfusion protocol)
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	No info on blinding ‐ may impact clinical decision‐making but not for our outcomes (low risk related to transfusion protocol)
Incomplete outcome data (attrition bias) All outcomes	High risk	Cross‐over of participants within trial without ITT analysis: 7 participants initially allocated to group B received autotransfusion drain and were included in group B
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Unclear risk	Funding and conflicts of interest not reported