Heddle 1992.

Study characteristics
Methods	Design: RCT, parallel two‐arm, multicentre study Setting: two hospitals (1 university teaching hospital, 1 regional hospital) in Ontario, Canada Recruitment: recruitment and study dates are not reported Maximum follow‐up: duration of hospital stay
Participants	81 participants undergoing elective knee arthroplasty were randomly assigned to one of two groups: Solcotrans group (Cell salvage/intervention group): N = 39. M:F 14:25. Mean (SD) age 69.3 (6.9) Control group: N = 40. M:F 14:26. Mean (SD) age 71.0 (9.0) There was no between‐group differences reported at baseline.
Interventions	Solcotrans group (Cell salvage/intervention group): the cell salvage group underwent drainage and autotransfusion using a Solcotrans system. The autologous blood collected into the drainage and transfusion device was transfused if specific transfusion guidelines were met. Participants were transfused the initial unit of Solcotrans blood if 350 mL or more had been collected within 3 hours of the patient's entry to the recovery room. The 3‐hour collection time provided for collection and transfusion of the blood within the maximum interval of 6 hours. After successful collection and transfusion of the first autologous blood unit, a second autologous blood collection device was attached. For this and subsequent collections, autologous blood was transfused if 150 mL or more was collected within 3 hours. When the rate of drainage was < 250 mL of blood within a 3‐hour period, a subsequent drainage and transfusion device was not attached. The first Solcotrans device attached to the drain contained 40 mL of ACD‐A. Control group: the control group had their drained blood collected by a Davol suction unit and discarded. The Davol unit was the current standard practice in the two study centres. Participants assigned to the Davol suction group received 1 unit of allogeneic red cells if > 500 mL of blood drained from the surgical site within a 2‐hour period. Subsequently, whenever drainage exceeded 500 mL within a 2‐hour period, 1 unit of allogeneic blood was transfused.
Outcomes	Outcomes reported: amount of allogeneic blood transfused, number of participants transfused allogeneic blood, adverse events, blood loss, coagulation variables, venogram tests
Notes	Transfusion protocol: on postoperative Day 2 through to Day 5, the criteria for allogeneic red cell transfusions were identical for both groups. Participants were given one unit of red cell concentrate if their haemoglobin was within the range of 8.0 to 8.9 g/dL, two units when the value was from 7.0 to 7.9 g/dL, three units when the value was from 6.0 to 6.9 g/dL, and four units if the value was from 5.0 to 5.9 g/dL. Prospective registration status: the study was published prior to 2010. Ethical approval: it is not clear whether the study was approved by an ethics committee or institutional review board. Language of publication: English Trial funding: not reported Conflicts of interest: not reported
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 of participants and personnel (performance bias) Objective outcome: mortality	Low risk	No objective outcomes reported (mortality unlikely to be affected by blinding if reported in future publications)
Blinding of participants and personnel (performance bias) Subjective: transfusion protocol	High risk	Transfusion protocol at high risk for inter‐participant variability: "As the study could not be double‐blind, strict transfusion criteria were developed for all study patients. The criteria by which allogeneic red cell transfusions were administered were established by the orthopedic surgeons participating in the study and reflected clinical practice in Canada.... Transfusion guidelines for Day 1 of the study had to be different for the two treatment groups because of the two interventions being studied."
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	High risk	The study was unblinded
Blinding of outcome assessment (detection bias) Objective outcomes: mortality and transfusions	Low risk	No objective outcomes reported (mortality unlikely to be affected by blinding if reported in future publications)
Blinding of outcome assessment (detection bias) Subjective outcomes	High risk	The study was unblinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	81 randomised, 79 analysed. 2 exclusions explained
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Unclear risk	No baseline imbalance noted. Funding and conflicts not reported