Mac 1993.

Study characteristics
Methods	Design: RCT, parallel two‐arm, single‐centre study Setting: private, non‐profit tertiary care hospital Recruitment: August 1990 to February 1991 Maximum follow‐up: 1 year postoperatively
Participants	Group 1 (Constavac) (Cell salvage/intervention): N = 56. Mean age 66.4. M:F (%) 50:50 Group 2 (Haemovac) (Control/no cell salvage): N = 35. Mean age 63.9. M:F (%) 37:63 There was baseline imbalance in ASA score between the groups.
Interventions	Group 1 (Constavac) (Cell salvage/intervention): postoperative autoreinfusion device Group 2 (Haemovac) (Control/no cell salvage): standard drain used postoperatively
Outcomes	Outcomes reported: blood loss, blood replacement, length of hospital stay
Notes	Transfusion protocol: on the day of surgery, blood was transfused at the discretion of the surgeon. On postoperative days 1 and 2, blood was transfused for a haemoglobin below "10 vols/100 mL". Prospective registration status: the study was published prior to 2010. Ethical approval: it is not clear whether the study was approved by an ethics committee or institutional review board. 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)	High risk	Original randomisation methods unclear. Randomisation was broken as 15 participants were reassigned after randomisation to ConstaVac group by operating surgeon
Allocation concealment (selection bias)	Unclear risk	Operating staff not aware of allocation until procedure but explicit method of concealment not reported e.g. sealed opaque envelopes
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	Decisions on blood transfusion varied depending on the day. Quote: "On the day of surgery, blood was transfused at the discretion of the surgeon. On postoperative days 1 and 2, blood was transfused for a haemoglobin below 10 vols/100ml."
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	Low risk	Intraoperative allocation only shared at end of operation. Postoperative transfusion threshold in place and standard care described as consistent. Physician blinded for most of the procedure until drain inserted.
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	High risk	Undefined protocol for LOS and blood loss measurement, once blinding was broken
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Poorly described
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	High risk	No conflict of interest or funding declaration. Baseline imbalance of groups (ASA grade) and uneven group size