Kirkos 2006.

Study characteristics
Methods	Design: RCT, parallel two‐arm, multicentre study Setting: two hospitals in Greece (one university teaching hospital (Thessaloniki, Greece) and 1 district general hospital (Kilkis, Greece)) Recruitment: during 2002. Recruitment and study dates not specified. Maximum follow‐up: 5 days postoperatively
Participants	155 participants undergoing total knee arthroplasty were randomly allocated to one of two groups: Group B (Autotransfusion group) (Cell salvage/intervention group): N = 78. M:F 18:60. Mean (SD) age 69.08 (5.45) Group A (Standard vacuum drain) (Control/no cell salvage group): N = 77. M:F 10:67. Mean (SD) age 68.88 (5.11) The study suggests groups were comparable at baseline; however, there was a higher percentage of males in Group B than in Group A.
Interventions	Group B1 (Autotransfusion group) (Cell salvage/intervention group): autotransfusion group had their drained blood that was collected within the first 6 hours postoperatively transfused through a standard blood transfusion set with 40 µm microaggregate filter. A standard 1000 mL blood transfer bag was connected to the system in order to collect and re‐transfuse the blood by gravity. Group A2 (Standard vacuum drain) (Control/no cell salvage group): control group received standard vacuum drains without autotransfusion.
Outcomes	Outcomes reported: amount of allogeneic blood transfused, days with fever, fever, volume of blood re‐transfused, haemoglobin levels
Notes	Transfusion protocol: participants were transfused allogeneic blood if haemoglobin level fell to < 10.0 g/dL. Prospective registration status: the study was published prior to 2010. Ethical approval: the study was approved by the hospital's Scientific Research 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)	High risk	Study allocated participants to intervention or control on an alternating basis. The first patient to participate in the study was classified in Group B, the second patient in Group A, and so on. If a Group B patient was withdrawn from the study during the operation, the next patient to participate in the study was again classified in Group B.
Allocation concealment (selection bias)	High risk	Study allocated participants to intervention or control on an alternating basis. The first patient to participate in the study was classified in Group B, the second patient in Group A, and so on. If a Group B patient was withdrawn from the study during the operation, the next patient to participate in the study was again classified in Group B.
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: "Patients with Hb level < 10 g/dL were transfused with allogeneic blood"
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	High risk	Differential management of wound closure and bleeding between groups
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	High risk	Differential management of wound closure and bleeding between groups
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	The total number of patients contributing to the outcome measures is not reported: states that 78 and 77 were per group. Unclear if this was the number randomised and/or number analysed. Would assume analysed, but therefore unclear whether this is ITT, or general info on patient flow
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	High risk	Funding and conflicts of interest not reported. Also states that "the patients in both groups were comparable with respect to their age and gender", but higher % of male in group B than group A (18/78 versus 10/77). Pre‐op Hb and platelet count similar. In discussion, they note differences/correlations due to gender, but do not comment that they actually had a gender imbalance.