Thomassen 2014.

Study characteristics
Methods	Design: RCT, parallel three‐arm, multicentre study Setting: 2 hospitals within the Netherlands Recruitment: November 2010 to November 2012 Maximum follow‐up: 6 weeks postoperatively
Participants	Adult participants undergoing primary THR or primary TKR were eligible. 575 participants were randomised to one of three treatment groups: Group A (No wound drainage) (Control/no cell salvage group): N = 190. M:F 58:132. Mean age 68.9. Mean BMI 28.2 Group B(Autologous blood reinfusion at 6 hours and drain removal at 6 hours) (cell salvage/intervention group): N = 191. M:F 68:123. Mean age 69.5. Mean BMI 28.2 Group C (Autologous blood reinfusion at 6 hours and drain removal at 24 hours) (cell salvage/intervention group): N = 194. M:F 74:120. Mean age 68.2. Mean BMI 28.1 Groups were comparable at baseline assessment.
Interventions	Group A (No wound drainage) (Control/no cell salvage group): no wound drainage was performed. Group B (Autologous blood reinfusion at 6 hours and drain removal at 6 hours) (cell salvage/intervention group): in Group B, salvaged blood was reinfused at 6 hours and the ABT drain was removed after 6 hours. Group C (Autologous blood reinfusion at 6 hours and drain removal at 24 hours) (cell salvage/intervention group): in group C, the re‐infusion drainage bottle was replaced with a low‐vacuum Bellovac drain (WellSpect Healthcare) after the first 6 hours, and then removed during the first postoperative morning (between 18 and 24 hours postoperatively). The re‐infusion drains were used in groups B and C according to the manufacturer’s instructions for postoperative autologous blood collection and re‐infusion. The collected shed blood was returned to participants in both reinfusion groups irrespective of their haemoglobin (Hb) level.
Outcomes	Primary outcome: proportion of postoperative participants receiving an allogeneic blood transfusion Secondary outcomes: perioperative blood loss (THR only), transfusion volumes, length of hospital stay, adverse events
Notes	Transfusion protocol: the decision to transfuse allogeneic blood was according to the restrictive Dutch transfusion threshold regime. Allogeneic transfusion was only given when the Hb level was > 8 g/dL in symptomatic patients; Hb 6.4 g/dL for patients ASA 1 or ASA 2‐3 undergoing uncomplicated surgery; Hb 8 g/dL for patients ASA 2‐3 undergoing surgery with blood loss > 500 mL; Hb 9.6 g/dL for ASA 2‐3 with minor complications during surgery. Prospective registration status: the study was retrospectively registered with a trials registry (Dutch Trials Registry No. NTR2501). Registration was 1 month after the study start date. Ethical approval: the study was approved by a medical ethics committee (NL27458.098.10). Language of publication: English Trial funding: benefits were received and directed solely to a research fund, foundation, educational institution, or other non‐profit organisation with which one or more of the authors are associated. Conflicts of interest: declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Stratification was carried out per clinic and variable block sizes were used to ensure 3 balanced groups were achieved. A computer‐generated randomisation plan was sealed in opaque envelopes by an independent person. Randomisation was performed in the operating theatre at the point of wound closure.
Allocation concealment (selection bias)	Low risk	A computer‐generated randomisation plan was sealed in opaque envelopes by an independent person
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	The decision to transfuse allogeneic blood was according to the restrictive Dutch transfusion threshold regime. Allogeneic transfusion was only given when the Hb level was > 8 g/dL in symptomatic patients; Hb 6.4 g/dL for patients ASA 1 or ASA2‐3 undergoing uncomplicated surgery; Hb 8 g/dL for patients ASA 2‐3 undergoing surgery with blood loss > 500 mL; Hb 9.6 g/dL for ASA2‐3 with minor complications during surgery. However, authors report that "37% of patients potentially transfused 'unjustifiably'".
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	Unclear risk	Study personnel were not blinded to treatment 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	The blinding status of outcome assessors is not described. However, adverse events are well‐defined.
Incomplete outcome data (attrition bias) All outcomes	Low risk	25 participants received incorrect treatment and so a per‐protocol analysis was performed as well as the ITT analysis
Selective reporting (reporting bias)	Low risk	A study protocol is available and was published prior to participant recruitment. All outcomes specified are reported within the study
Other bias	High risk	Support provided by a pharmaceutical company: "Representatives from the company were involved in the study design, data analysis and preparation of the manuscript. The funder has supported in the planning, conduct and reporting of the study. They have contributed with writing the study protocol and manuscript, organized study meetings, monitored the data and data analysis". No baseline imbalance noted.