Kirkos 2006.

Methods	This prospective randomised trial evaluated the safety and efficacy of post‐operative blood retrieval and re‐infusion in patients undergoing total knee arthroplasty for primary knee osteoarthritis during 2002. Method of randomisation and allocation concealment was not described.
Participants	155 patients undergoing total knee arthroplasty were randomly allocated to one of two groups: Group 1 (Autotransfusion group): n=78; M/F=18/60; mean (sd) age = 69.08 (5.45) years Group 2 (Control group): n=77; M/F=10/67; mean (sd) age = 68.88 (5.11) years
Interventions	Group 1: Autotransfusion group had their drained blood that was collected within the first 6 hours post‐operatively, transfused through a standard blood transfusion set with a standard blood transfusion set with a 40um microaggregate filter. A standard 1000ml blood transfer bag was connected to the system in order to collect and re‐transfuse the blood by gravity. Group 2: 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 threshold: patients were transfused allogeneic blood if the haemoglobin level fell to less than 10.0g/dL.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Study allocated patients 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 discarded from the study during the operation the next patient to participate in the study was again classified in Group B.
Allocation concealment (selection bias)	Unclear risk	Method used to conceal treatment allocation was not described.
Blinding (performance bias and detection bias) All outcomes	High risk