Adalberth 1998.

Study characteristics
Methods	Deisgn: RCT, parallel three‐arm, single‐centre study Setting: university teaching hospital, Uppsala, Sweden Recrutiment: recruitment and study dates are not reported Maximum follow‐up: duration of hospital stay
Participants	90 participants undergoing primary total knee arthroplasty were randomised to one of three groups: No drain group: N = 30. M:F 11:13. Mean (95% CI) age 70 (67 to 74) Solcotrans drain group (Cell salvage/intervention group): N = 30. M:F 4:20. Mean (95% CI) age 71 (69 to 74) Standard (Redon) drain group (Control/no cell salvage group): N = 30. M:F 9:16. Mean (95% CI) age 72 (69 to 75) Of the 90 participants included in the study, 73 remained for analysis. Patients with DVT, drainage failure, lost study values, or those given NSAIDs were excluded. For the purpose of our analysis, we included data from the Solcotrans drain group as the intervention group and the Standard (Redon) drain group as the control group.
Interventions	No drain group: no drain was used. Solcotrans drain group: Solcotrans autotransfusion system collected blood for 6 hours or until the unit was full. Acid citrate dextrose‐anticoagulant (ACD‐A) was not added to the collection unit. Continuous suction was applied at 20 cm H2O. Drains were maintained for 24 hours postoperatively. Standard (Redon) drain group: a standard disposable closed suction drainage system (Redon) was used with two standard drains maintained for 24 hours postoperatively.
Outcomes	Outcomes reported: number of participants transfused allogeneic blood, blood loss, hospital length of stay, Hb and Hct levels
Notes	Transfusion protocol: allogeneic blood transfusion was given if the haemoglobin level was < 9.0 g/dL. Prospective registration status: the study was published prior to 2010. Ethical approval: the study was approved by the Ethics Committee at Uppsala University Hospital. 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	Randomisation process not described
Allocation concealment (selection bias)	Unclear risk	Sealed envelopes were used to conceal treatment allocation, but doesn't mention opaqueness of 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	Low risk	Transfusion protocol: allogeneic blood transfusion was given if the haemoglobin level was < 9.0 g/dL.
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	High risk	All outcomes lack clear guidelines
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	All outcomes lack clear guidelines
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	20% attrition rate, even across the three groups; those excluded were due to adverse events (unclear if AEs due to intervention or if DVT etc. noted at baseline and were incorrectly included)
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Unclear risk	No mention of funding or conflicts