Horstmann 2012.

Study characteristics
Methods	Design: RCT, parallel two‐arm, single‐centre study Setting: non‐academic regional hospital, Zwolle, the Netherlands Recruitment: February 2007 to April 2008 Maximum follow‐up: 3 months postoperatively
Participants	100 participants scheduled for primary total hip replacement were enroled and randomised to one of the following groups: Autotransfusion group (Cell salvage/intervention group): N = 50. Mean (SD) age 68.6 (9.1). M:F 13:37. Mean (SD) BMI 28.1 (4.5). Control group: N = 50. Mean (SD) age 69 (9.2). M:F 14:36. Mean (SD) BMI 27.6 (3.8). The groups were similar with regard to demographic data and baseline variables, other than mean operation time, which was longer in the no drainage group.
Interventions	Autotransfusion group (Cell salvage/intervention group): postoperative autotransfusion using the Bellovac ABT system (Astra Tech, Mölndal, Sweden). The drain was inserted at the end of the procedure and low suction (60 to 90 mmHg) was started. Re‐transfusion was performed within 6 hours after surgery and was not allowed to exceed 1500 mL. Drains were removed after 24 hours. Control group: control group for whom no drain was inserted.
Outcomes	Outcomes reported: blood loss during surgery, homologous blood transfusion, incidence of haematomas, amount of drained and re‐transfused wound blood, wound healing disturbances, postoperative pain, length of hospital stay, adverse events, Harris Hip Score, physical and mental SF‐36 scores, total blood loss
Notes	Transfusion protocol: homologous transfusion was given based on Dutch guidelines, with a trigger of 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 and in patients that failed to increase cardiac output to compensate for dilution Prospective registration status: the study was not prospectively registered with a trial registry. Ethical approval: the study received approval from the Institutional Medical Ethics Committee, Isala Clinics, Zwolle, the Netherlands. Language of publication: English Trial funding: not reported Conflicts of interest: none reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation methodology not provided
Allocation concealment (selection bias)	Low risk	Participants were randomised to intervention or control using numbered, concealed envelopes containing pre‐randomised cards
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	Low risk	Transfusion protocol in place: additional homologous blood transfusions were given based on the Dutch homologous blood transfusion guidelines. The trigger for homologous transfusions was an Hb level of 6.4 g/dL in American Society of Anesthesiologists (ASA) 1 patients, 8.0 g/dL in ASA 2/3 patients, and 9.6 g/dL in ASA 4 patients and in patients that failed to increase their cardiac output to compensate for dilution
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	Low risk	Clear method for measuring blood loss described. Outpatient caregivers blinded to group allocation.
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	Low risk	Doctors reviewing participants at follow‐up in the outpatient clinic were blinded to their treatment allocation; however, it is unclear whether outcome assessment of outcomes reported during the admission was blinded
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No information provided for patient flow, or N analysed
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Low risk	Conflicts declared, no baseline imbalance