Methods	Patients with severe hip arthrosis undergoing total hip arthroplasty were studied to evaluate the efficacy of different peri-operative blood saving techniques to reduce allogeneic blood transfusion. Method of randomisation and allocation concealment was not described
Participants	45 patients undergoing total hip arthroplasty were randomly allocated to one of three groups: Group 1 (Control group): n=15 Group 2 (Autotransfusion group): n=15 Group 3 (Autologous predonation + autotransfusion group): n=15 NB: Demographic data were not reported.
Interventions	Group 1 (Control group): blood loss was replaced with heterologous erythrocyte concentrate (SAGM-ERC) and 3% dextran 60 in a ratio of 1:1. If necessary, additional SAGM-ERC was transfused to correct erythrocyte volume fraction (EVF)>27%. Group 2 (Autotransfusion group): blood loss was replaced with 3% dextran and by autotransfusion of washed and haemconcentrated blood salvaged by intraoperative suction and from wound drains up to 4 hours postoperatively. As in Group 1, additional SAGM-ERC was transfused to correct erythrocyte volume fraction (EVF)>27%. Group 3 (Autologous predonation + Cell Saver group): blood loss was replaced with 3% dextran and by autotransfusion of washed and haemconcentrated blood salvaged by intraoperative suction and from wound drains up to 4 hours postoperatively. Predonated autologous SAGM-ERC was used instead of heterologous blood to maintain erythrocyte volume fraction (EVF)>27%. In 2-3 sessions within 6 weeks prior to the operation, 2 to 3 units of SAGM-ERC had been withdrawn. If necessary, heterologous SAGM-ERC was used if transfusion of all predonated autologous blood failed to maintain EVF>27%. Autotransfusion technique: Haemonetic Cell Saver 4, Althin model AT 1000, or Shiley/Dideco STAT were used. Blood was retrieved from the operation site by suction through a double lumen catheter and was then anticoagulated with heparin (30,000 IU heparin in 1000ml of physiological saline). The blood was collected into a reservoir where a macrofilter removed debris. Thereafter, the blood was pumped into a spinning centrifuge bowl (125ml of blood) and washed with 1500ml of physiological saline. The erythrocytes were concentrated to an EVF of about 50-60% and pumped into an infusion bag. The effluent containing platelets, free haemoglobin and anticoagulants was disposed
Outcomes	Outcomes reported: amount of allogeneic blood transfused, amount of autologous blood transfused, number of patients transfused allogeneic blood, complications, adverse events
Notes	Transfusion threshold: patients were transfused allogeneic blood to maintain the erythrocyte volume fraction (EVF) >27%
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 (performance bias and detection bias) All outcomes	High risk