Methods	Patients admitted for elective primary joint replacement surgery were enrolled in this randomised controlled trial. Patients were randomised using a computer-generated randomisation table. Method of allocation concealment was not described
Participants	99 patients undergoing elective primary total knee replacement surgery were randomly allocated to one of two groups: Group 1 (Autotransfusion group): n=44 Group 2 (Control group): n=55 NB: Demographic data not reported.
Interventions	Group 1: Autotransfusion group had blood salvage performed using a semiautomated autotransfuser (Electromedics BT-795) according to the manufacturer’s instructions. Intra-operative blood salvage was performed by a nurse in conjunction with an anaesthetist. Post-operative blood salvage was a continuation of the intra-operative salvage for a duration not exceeding 6 hours after the tourniquet was released. On completion of salvage, the wound drains were connected to two vacuum-charged Redivac bottles and the drains were removed at 48 hours post operation. The average volume of blood salvaged in each patient was calculated after adjusting the haematocrit to 40%. Group 2: Control group received no autotransfusion. NB: In total knee replacement patients, standard surgical technique using a midline incision and medial parapatellar approach under tourniquet control was followed, and lateral release of the quadriceps expansion was not routinely performed
Outcomes	Outcomes reported: number of patients transfused allogeneic blood, blood loss.
Notes	Transfusion threshold: allogeneic blood transfusions were used intra/post-operatively to maintain a safe blood volume and a haemoglobin level around 10.0g/dL
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Patients were randomised using a computer-generated randomisation table
Allocation concealment (selection bias)	Unclear risk	Method used to conceal treatment allocation was unclear.
Blinding (performance bias and detection bias) All outcomes	High risk