Ayers 1995.

Methods	The study was conducted between October 15, 1991 through to January 1, 1993. The patients included 125 women and 107 men who were 20‐89 years of age (mean age = 72 years). All patients were advised to donate blood pre‐operatively. The 156 patients (67%) who were scheduled to have a primary procedure were advised to donate 2 units of autologous blood, and the 76 patients (33%) who were scheduled to have a revision procedure were a advised to donate 4 units of autologous blood.
Participants	232 patients undergoing total hip arthroplasties were randomly assigned to one of two groups: Group 1 (Autotransfusion group): n=103 Group 2 (Control group): n=129 NB: Demographic data were not reported.
Interventions	Group 1: Autotransfusion group (Autovac Post‐operative Orthopaedic Autotransfusion Canister) had blood loss collected for 4 hours post‐operatively. The autotransfusion canister was injected with 40mls 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 100mmHg. If at least 300mls of blood was collected within 4 hours, the unwashed blood was reinfused through a microaggregate filter; if less than 300mls 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. Group 2: Control group had a closed suction drainage system used (Hemovac system).
Outcomes	Outcomes reported: number of patients transfused allogeneic and./or autologous blood, blood loss, Hb levels.
Notes	Transfusion threshold: Transfusion protocol not reported. All revision patients were exposed to cell salvage intra‐operatively. 85% of Group 1 patients pre‐deposited blood pre‐operatively (PAD). 77% of Group 2 patients pre‐deposited blood pre‐operatively (PAD).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Patients were randomly assigned on the basis of their hospital record number.
Allocation concealment (selection bias)	High risk	Inadequate allocation concealment.
Blinding (performance bias and detection bias) All outcomes	High risk