Ayers 1995.

Study characteristics
Methods	Design: RCT, parallel two‐arm, multicentre study Setting: regional hospital and university teaching hospital, Syracuse, NY, USA Recruitment: October 1991 to January 1993 Maximum follow‐up: duration of hospital stay
Participants	232 participants undergoing total hip arthroplasty were randomly assigned to one of two groups: Postoperative Blood Salvage group (Cell Salvage/intervention group): N = 103. N primary procedure = 67 (65%). N revision procedure = 36 (35%). Closed suction (Haemovac) drain group (Control/no cell salvage group): N = 129. N primary procedure = 89 (69%). N revision procedure = 40 (31%). No demographic data were reported, but the study reports that the two groups were similar in all respects.
Interventions	Postoperative Blood Salvage group (Cell Salvage/intervention group): cell salvage group (Autovac Post‐operative Orthopaedic Autotransfusion Canister) had blood loss collected for 4 hours postoperatively. The autotransfusion canister was injected with 40 mL of acid‐citrate‐dextrose anticoagulant (ACD‐A) before activation. The autotransfusion canister was connected to wall suction with use of an Autovac Autotranfusion Regulator that limited maximum collection pressure to 100 mmHg. If at least 300 mL of blood was collected within 4 hours, the unwashed blood was reinfused through a microaggregate filter; if < 300 mL of blood was collected, the blood was discarded. Any blood that had not been reinfused within 6 hours after the beginning of collection was discarded. Closed suction (Haemovac) drain group (Control/no cell salvage group): control group had a closed suction drainage system used (Hemovac system). All participants were advised to donate blood pre‐operatively. The 156 participants (67%) who were scheduled to have a primary procedure were advised to donate 2 units of autologous blood, and the 76 participants (33%) who were scheduled to have a revision procedure were advised to donate 4 units of autologous blood.
Outcomes	Outcomes reported: number of participants transfused allogeneic and/or autologous blood, blood loss, Hb levels
Notes	Transfusion protocol: use of a transfusion protocol is not reported. All revision participants were exposed to cell salvage intraoperatively. 85% of Group 1 participants pre‐deposited blood pre‐operatively (PAD). 77% of Group 2 participants pre‐deposited blood pre‐operatively (PAD). Prospective registration status: the study was published prior to 2010. Ethical approval: it is unclear whether the study was approved by an institutional review board or ethics committee. 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)	High risk	Randomly assigned on the basis of their hospital number – possibly quasi‐RCT – but unclear how the hospital number was used (may be properly randomised). All those who had revision procedure had cell salvage
Allocation concealment (selection bias)	High risk	Inadequate allocation concealment. No info on most, but all who had a revision (not primary) procedure had cell salvage
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	Protocol in reference to how patients are monitored not indication for transfusion
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	High risk	A large number definitely knew their allocation to cell salvage
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	A large number definitely knew their allocation to cell salvage
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	The number of participants analysed is not reported: unclear patient flow, and unclear how many were used for each analysis as there appears to be subgrouping by those who had pre‐donated autologous blood
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Unclear risk	No mention of funding or conflicts