Horstmann 2014a.

Study characteristics
Methods	Design: RCT, parallel two‐arm, single‐centre study Setting: non‐academic regional hospital, Zwolle, the Netherlands Recruitment: recruitment and study dates not reported Maximum follow‐up: 3 months postoperatively
Participants	118 participants undergoing primary elective total hip replacement were randomised to one of two groups. Autologous blood transfusion (ABT) drain group (Cell salvage/intervention group): N = 56. Mean (SD) age 67.6 (9.1). M:F 20:36. Mean (SD) BMI 27.8 (4.4). Drain group (Control/no cell salvage group): N = 62. Mean (SD) age 69.3 (9.5). M:F 20:42. Mean (SD) BMI 28.1 (4.4). The groups were similar with regard to demographic and baseline data, except for operation time, which was longer in the drainage (control) group.
Interventions	Autologous blood transfusion (ABT) drain group (Cell salvage/intervention group): participants in the ABT (Cell Salvage) group had intraoperative and postoperative cell salvage and autotransfusion performed using the Sangvia ABT system (intraoperative and postoperative autologous blood salvage unit, low vacuum, 100 to 150 mmHg, Astratech, Mölndal, Sweden). Blood salvaged during the operation was re‐transfused and a drain for postoperative salvage was inserted at the end of the procedure. Postoperatively drained blood was re‐transfused within 6 hours after surgery. Drain group (Control/no cell salvage group): participants in the drain group (control group) received a standard high suction drain (Redon, Medinorm AG, Quierschied, Germany). No autotransfusion was performed. The drains were removed 24 hours after surgery in both groups.
Outcomes	Outcomes reported: blood loss during surgery, volume of intraoperatively suctioned and re‐transfused blood, volume of re‐transfused drained wound blood, allogeneic blood transfusions, postoperative pain, hospital stay, adverse events, total blood loss
Notes	Transfusion protocol: allogeneic transfusions were given according to Dutch guidelines. The trigger was 6.4 g/dL in American Society of Anesthesiologists (ASA) 1 patients, 8 g/dL in ASA 2/3 patients, and 9.6 g/dL in ASA 4 patients or those whose cardiac output failed to increase to compensate for dilution. Prospective registration status: the study was not prospectively registered with a trial registry. Ethical approval: the study was approved by the Institutional Medical Ethics Committee, Isala Clinics, Zwolle, the Netherlands. 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	Authors do not state how the randomisation sequence was generated e.g. computer‐generated sequence?
Allocation concealment (selection bias)	Low risk	Participants were randomised to one of two groups using sealed and numbered, opaque enveloped containing pre‐randomised cards.
Blinding of participants and personnel (performance bias) Objective outcome: mortality	Low risk	Objective outcome (mortality) unlikely to be influenced by blinding
Blinding of participants and personnel (performance bias) Subjective: transfusion protocol	Low risk	Transfusion protocol in place: additional allogeneic blood transfusions were given based on the Dutch allogeneic blood transfusion guidelines. The trigger for allogeneic transfusions was an Hb level of 6.4 g/dL in patients with American Society of Anaesthesiologists (ASA) physical classification 1, 8.0 g/dL in ASA classifications 2 and 3, and 9.6 g/dL in ASA classification 4, as well as in those whose cardiac output failed to increase to compensate for dilution.
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	Unclear risk	Insufficient information about postoperative care received and blinding status. Surgeons were blinded during the operation until the last available opportunity, which would help to mitigate performance bias during the operation.
Blinding of outcome assessment (detection bias) Objective outcomes: mortality and transfusions	Low risk	Objective outcome (mortality) unlikely to be influenced by blinding
Blinding of outcome assessment (detection bias) Subjective outcomes	Low risk	Insufficient information about postoperative care received and blinding status. Surgeons were blinded during the operation until the last available opportunity, which would help to mitigate performance bias during the operation.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants are accounted for at 3‐month outcome measurements. ITT, all participants accounted for in analysis, although authors do not make a definitive statement on whether there were any dropouts or losses to follow‐up.
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Unclear risk	Only significant difference between groups at baseline (prior to autotranfusion) was operation time (P < 0.04). No information provided regarding conflicts of interest or funding