Eng 1990.

Study characteristics
Methods	Design: RCT, parallel two‐arm, single‐centre study Setting: university teaching hospital, Leeds, Yorkshire, UK Recruitment: recruitment and study dates not reported Maximum follow‐up: duration of hospital stay
Participants	40 participants (33 males and 7 females) undergoing elective coronary artery bypass surgery were randomised to one of two groups: Study group (Cell salvage/intervention group): N = 20 Control group: N = 20 Mean (range) age for both groups = 55.75 (33 to 69) years. The authors report no differences in demographic data or pre‐operative variables between the groups at baseline.
Interventions	Study group (Cell salvage/intervention group): received postoperative autologous blood transfusion (AT) using the Shiley hardshell venous reservoir. At the end of the operation in theatre, the chest drains were connected to the Shiley hardshell venous reservoir using the Shiley drainage set. After the system was primed and specimens obtained for haematological, biochemical, and bacteriological analyses, transfusion of the shed blood was commenced, the rate depending on the amount of drainage, reinfusing the previous hour's blood loss over the subsequent hour. At the end of 6 hours, the AT was discontinued, and further specimens were obtained. Control group: participants were managed in the same manner without the use of autologous blood transfusion.
Outcomes	Outcomes reported: amount of blood re‐transfused from the cell saver, amount of allogeneic blood transfused, number of participants transfused allogeneic blood, hospital length of stay, mortality, blood loss, adverse events
Notes	Transfusion protocol: allogeneic blood transfusion was used only when the haematocrit fell below 25%, haemoglobin below 9.0 g/dL or the blood loss exceeded 500 mL in the first 4 hours. Prospective registration status: the study was published prior to 2010. Ethical approval: the study was approved by the Hospital Ethics Committee. 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	Method used to generate allocation sequences was not described
Allocation concealment (selection bias)	Unclear risk	Method used to conceal treatment allocation was unclear
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: blood was used only when the haematocrit fell below 25%, haemoglobin below 9 g/dL or the blood loss exceeded 500 mL in the first 4 hours
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	High risk	No mention of blinding of participants or personnel; may impact clinical decision‐making for blood loss and re‐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	High risk	No mention of blinding of participants or personnel; may impact clinical decision‐making for blood loss and re‐operation
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No info on participant flow: 40 participants randomised, unclear how many were analysed. Likely that all 40 were, based on baseline characteristics mentioned in the text (33M, 7F), but this is not clear
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Unclear risk	No baseline imbalance noted, though there is no breakdown of baseline characteristics per group, so relying on their statement that groups were similar. Funding and conflicts not reported