Shore‐Lesserson 1999.

Methods	Two‐group parallel RCT, one centre ITT: yes Funding: not for profit Overall study quality: low risk of bias Sample size calculation was reported
Participants	Inclusion criteria: adult cardiac surgical patients at moderate to high risk of microvascular bleeding and thus had a moderate to high risk for requiring a transfusion. Included patients underwent single valve replacement, multiple valve replacement, combined coronary artery bypass plus valvular procedure, cardiac reoperation, or thoracic aortic replacement. Patients receiving preoperative heparin infusion and those who had taken aspirin within the past 7 days were included Exclusion criteria: significant preexisting hepatic disease (transaminase levels > 2 times control) or renal disease requiring dialysis, or if they required preoperative inotropic support
Interventions	Intervention group: TEG‐guided transfusion algorithm group for intervention after cardiopulmonary bypass (n = 53) Transfusion algorithm was fully based on TEG. Type of TEG: Celite and tissue factor‐activated TEG, heparinase‐modified Celite‐activated TEG Control group: routine transfusion therapy for intervention after cardiopulmonary bypass, standard laboratory coagulation testing (n = 52) Duration of intervention: algorithms were used as long as the patient was still in the operating room Concomitant treatment: all patients were given prophylactic antifibrinolytic therapy (e‐aminocaproic acid). Anticoagulation for CPB was accomplished with bovine lung heparin. PRBCs were transfused when the haematocrit was < 25%. During cardiopulmonary by‐pass (CPB), a haematocrit of 21% was accepted
Outcomes	Primary: reduction in transfusion requirements Secondary: Coagulation tests, TEG variables, postoperative blood loss into mediastinal drainage at 6‐hour intervals for 2 days postoperatively, platelet count, PT, aPTT, fibrinogen level, TEG variables
Notes	Country: USA, Language: English Letter sent to authors in April and June 2010. Reply received in April 2010 Follow‐up: until hospital discharge, but transfusion requirements were reported for 2 days postoperatively "One patient in the control group who received numerous transfusions of PRBC and non‐PRBC components was excluded from analysis because a surgical source of bleeding was present on reexploration. Had this patient’s data been included, the difference in transfusions between the two groups would have been even greater, merely strengthening the results" "Significant bleeding was defined objectively as >100 mL in a 3‐min period or subjectively as the absence of visible clots in the surgical field" Lost to follow‐up:"One patient enrolled but not studied was undergoing cardiac reoperation and was placed emergently on CPB because of massive haemorrhage during sternotomy. The patient was excluded from the study at this time. The other patient who did not complete the protocol was excluded due to a severe protamine reaction that required immediate reinstitution of CPB. Both of these patients were in the TEG group" Authors conclusion:"We conclude that the reduction in transfusions may have been due to improved haemostasis in these patients who had earlier and specific identification of the haemostasis abnormality and thus received more appropriate intraoperative transfusion therapy. These data support the use of TEG in an algorithm to guide transfusion therapy in complex cardiac surgery. Implications: Transfusion of allogeneic blood products is common during complex cardiac surgical procedures. In a prospective, randomised trial, we compared a transfusion algorithm using point‐of‐care coagulation testing with routine laboratory testing, and found the algorithm to be effective in reducing transfusion requirements"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Central generation of table of random numbers.
Allocation concealment (selection bias)	Low risk	Sealed opaque envelopes.
Blinding (performance bias and detection bias) All outcomes	Low risk	"The anaesthesiologist and surgeon caring for the patient were blinded to the patient’s group assignment. All intraoperative results of the TEG and laboratory coagulation tests were interpreted by an anaesthesiologist investigator not directly involved with the patient’s care. The recommended therapy according to the patient’s group assignment was communicated to the anaesthesiologist and surgeon by this investigator, as appropriate." Data entry person was blinded to group assignment. Transfusions in the ICU after the first postoperative hour were performed at the discretion of the ICU physician, who was blinded to the patient’s group assignment.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Adequate follow‐up.
Selective reporting (reporting bias)	Low risk	Yes. Unable to compare with protocol or trial registration but appears to be free of selective reporting.
Other bias	Low risk	Adequate.