Methods	Consecutive patients undergoing total hip or total knee replacement procedures between January 1989 and April 1989 were included in this study. A computer-generated random number list was used to pre-operatively assign patients to intervention or control groups. Method used to conceal treatment allocation was not described
Participants	239 consecutive patients undergoing total knee replacement procedures were randomly assigned to one of two groups: Group 1 (Autotransfusion group): n=124; M//F=59//65; mean age = 65 years Group 2 (Control group): n=115; M//F=46//69; mean age = 69 years
Interventions	Group 1: Autotranfusion group (Solcotrans autotransfusion system) had their wounds drained into post-operative blood salvage canisters. There was a 6 hour total time limit for collection and reinfusion of blood. Because 40ml of citrate ACD-A was entered in each Solcotrans canister prior to use, a minimum of 320mls of blood and citrate volume was necessary before reinfusion to prevent citrate toxicity. If wound drainage was slow and an adequate volume had not been collected before the 6-hour time limit, the canister and blood were discarded, and a standard collection canister was attached to the drainage tube for the duration. If wound drainage was rapid, the canister was allowed to fill completely (500mls volume). The blood was then infused at an appropriate rate as long as the 6-hour pre-canister limit was not exceeded. Another Solcotrans canister could then be attached, beginning a new 6-hour time interval. Intra-operative blood salvage was not used. Group 2: Control group had their wounds drained into standard 400ml suction canisters. Autotransfusion was not performed.
Outcomes	Outcomes reported: amount of blood re-transfused from the cell saver, number of patients transfused allogeneic blood, adverse events
Notes	Transfusion threshold: All patients whose post-operative haemoglobin value was less than 9.0g/dL were transfused allogeneic blood. The decision to transfuse patients with haemoglobin values greater than 9.0g/dL was made by the internist on the basis of each patient’s medical condition
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A computer-generated random number list was used to pre-operatively assign patients to either intervention or control
Allocation concealment (selection bias)	Unclear risk	Method used to conceal treatment allocation was unclear.
Blinding (performance bias and detection bias) All outcomes	High risk