Elawad 1991.

Study characteristics
Methods	Design: RCT, parallel two‐arm, single‐centre study Setting: university teaching hospital, Malmo, Sweden Recruitment: recruitment and study dates not reported Maximum follow‐up: 24 hours postoperatively
Participants	40 participants undergoing primary total hip arthroplasty were randomly allocated to one of two groups: Autologous group (Cell salvage/intervention group): N = 20. M:F 9:11. Mean (range) age 68 (59 to 89) Homologous group (Control/no cell salvage group): N = 20. M:F 8:12. Mean (range) age 74 (48 to 89) The authors do not state whether there were any between‐group differences at baseline.
Interventions	Autologous group (Cell salvage/intervention group): cell salvage group received autologous blood processed intraoperatively by a cell saver device (Electromedic Autotrans AT1000 autotransfusion system). Blood was retrieved from the operative field with a double lumen suction catheter. The blood was immediately anticoagulated with sodium citrate. Larger debris was removed by a 240 µm filter in the cardiotomy reservoir. The filtered blood was pumped into a bowl centrifuge and washed with 1500 mL of saline. The supernatant was discarded. The erythrocyte concentrate was pumped into a reinfusion bag and then reinfused into the patient. Homologous group (Control/no cell salvage group): control group received allogeneic blood and no autotransfusion.
Outcomes	Outcomes reported: amount of allogeneic units transfused, number of participants receiving allogeneic blood, complications, blood loss
Notes	Transfusion protocol: the indications for blood transfusion were the same in both groups. Intraoperatively, blood was given according to the anaesthetist’s decision. Postoperatively, a transfusion was given if the haemoglobin was < 85 g/L or if there were symptoms of anaemia. 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	Does not state whether sealed envelopes are also opaque
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 in place but intraoperative transfusion according to clinician decision: intra‐op high ROB as decided by the clinician. Transfusion protocol post‐op only: "The indications for blood transfusion were the same in both groups. Intraoperatively, blood was given according to the anesthetist’s decision. Postoperatively, a transfusion was given if the hemoglobin was < 85 g/L or if there were symptoms of anemia (Grindon et al. 1985)"
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	High risk	Variable techniques for blood loss measurement; no description for other outcomes
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 blinding status of participants and personnel was not described but transfusion decisions according to clinician preference intraoperatively
Incomplete outcome data (attrition bias) All outcomes	Low risk	One participant was excluded due to logistical failures
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Unclear risk	Baseline imbalance marginal (age range included younger patients in control group but mean was similar). Funding and conflicts not reported