Methods	A controlled, randomised, prospective study was performed evaluating the need for perioperative blood salvage for primary total hip arthroplasty patients who had donated autologous blood before surgery. Patients were randomised by month of birth into four groups
Participants	153 patients undergoing primary total hip arthroplasty were randomised to one of four groups: Group 1 (Autotransfusion group - Haemonetics system): n=35; M//F=19//16; mean age = 68 years (range 50-86 years) Group 2 (Autotransfusion group - Solcotrans system): n=40; M//F=24//16; mean age = 68 years (range 28-87) Group 3 (Control group - Hemovac drainage system): n=38; M//F=20//20; mean age = 64 years (range 39-85 years) Group 4 (Control group - No drainage system): n=38; M//F=20//18; mean age = 61 years (range 38-86)
Interventions	Group 1: Autotransfusion group (Haemonetics system) had intra-operative salvage of red blood cells performed with the Haemonetics Cell-Saver. A paediatric bowl was used for the processing of salvaged, shed blood. This collection was continued after surgery through two medium drains while the patient remained in the recovery room. A closed-suction standard Hemovac drain was placed when salvage was discontinued. Group 2: Autotransfusion group (Solcotrans system) were treated with a Solcotrans drainage infusion system at the completion of surgery. This system consists of a 500ml collection canister with 260 micron pre-transfusion filter for collection and a 40 micron filter for transfusion. A minimum of 300 mls of blood had to be collected within a 4 hour period. Total collection/infusion time could not exceed 6 hours. A maximum of 2 units could be reinfused. After the completion of the transfusions, the Solcotrans unit was discarded and replaced with a closed-suction drain. Group 3: Control group (Hemovac drainage system) were treated with a standard 400ml Hemovac closed-suction drain. Group 4: Control group did not receive drains at the completion of surgery.
Outcomes	Outcomes reported: amount of allogeneic and/or autologous blood transfused, number of patients transfused allogeneic blood, adverse events, Hb & Hct levels, thigh circumference measures, wound drainage
Notes	Transfusion threshold: all decisions for allogeneic blood transfusion were based on the clinical condition of the patient. The absolute value of the haemglobin or haematocrit was not considered in isolation. Patients who were able to donate at least 2 units of autologous blood pre-operatively were included in the study
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)	High risk	Method used to conceal treatment allocation was inadequate.
Blinding (performance bias and detection bias) All outcomes	High risk