Cheung 2010.

Study characteristics
Methods	Design: RCT, parallel three‐arm, single‐centre study Setting: Specialist Orthopaedic Hospital, Oswestry, Shropshire, UK Recruitment: July 2005 to August 2006 Maximum follow‐up: 12 months postoperatively
Participants	168 participants undergoing primary total hip replacement for osteoarthritis were randomised to one of the following three groups: Group 1 (Cell salvage/intervention group): N = 53. Median (IQR) age 65 (61 to 73). M:F 22:39. Median (IQR) BMI 29 (26 to 33). Group 2 (Control/no cell salvage group): N = 52. Median (IQR) age 70.5 (63 to 76). M:F 24:30. Median (IQR) BMI 26.3 (24.3 to 29.5). Group 3 (Control/no cell salvage group): N = 48. Median (IQR) age 69 (62.3 to 76). M:F 23:30. Median (IQR) BMI 27 (25 to 29).
Interventions	Group 1 (Cell salvage/intervention group): autologous blood transfusion group (ABT) received a Bellovac ABT drain (Astra Tech Ltd., Gloucestershire, UK) (size 12). If deemed necessary, autologous transfusion was performed within 6 hours of collection. The drain was removed at 24 hours postsurgery. Group 2 (Control/no cell salvage group): the standard drain group received a standard suction drain (size 12). The drain used was a High Vaccuum Medinorm drain (Van Straten, Quiershield, Germany). The drain was removed at 24 hours postsurgery. Group 3 (Control/no cell salvage group): the no drain group did not have a drain inserted
Outcomes	Primary outcome: transfusion rate (proportion of participants), volume of blood administered Secondary outcomes: blood loss (intraoperative), postoperative haemoglobin concentration, wound infection rate, time for wound to become dry, length of hospital stay, investigation and treatment for thromboembolic events
Notes	Transfusion protocol: the decision about whether to transfuse was made by the ward doctors or anaesthetist. No criteria were set to trigger a transfusion, although all doctors at the trust had attended a transfusion awareness lecture, outlining broad guidelines. Prospective registration status: the study was retrospectively registered on a trials registry, 18 months after study commencement. Ethical approval: the study received ethics approval from the local research ethics committee for Robert Jones and Agnes Hunt Orthopaedic and District Hospital, Oswestry, Shropshire, UK Language of publication: English Study groups: for the purpose of our review, Group 2 and Group 3 were used as the "control/no cell salvage" group in the comparison against Group 1, the "cell salvage/intervention" group. Trial funding: no benefits of funds were received in support of the study Conflicts of interest: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Patients undergoing primary total hip replacement were randomised to one of three groups using stratified randomisation software (StratOs, Cooked Bits, Oswestry, UK) to balance the groups according to potentially confounding factors. The software used the Pocock and Simon implementation of the minimisation method. Prognostication was based on four prognostic factors: body mass index (BMI), age, gender and the use of aspirin and non‐steroidal anti‐inflammatory drugs (NSAIDs).
Allocation concealment (selection bias)	Low risk	It is unlikely that sequence allocation could be anticipated given the randomisation methodology used
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	High risk	No transfusion protocol in place: the decision about whether to transfuse was made by the ward doctors or anaesthetist. No criteria were set to trigger a transfusion, although all doctors at the trust had attended a transfusion awareness lecture, outlining broad guidelines.
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	High risk	No blinding, no strict guidelines for subjective outcomes
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	High risk	No blinding, no strict guidelines for subjective outcomes
Incomplete outcome data (attrition bias) All outcomes	Low risk	15 of 163 participants initially randomised were subsequently excluded after re‐checking of the exclusion criteria. Groups remained broadly even in size, no other loss to follow‐up
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Unclear risk	Conflicts not reported. Baseline imbalance in BMI between groups. Funding was reported.