Cooper 2011.

Study characteristics
Methods	Design: RCT, parallel 2‐arm, 2‐site trial Setting: 2 VA hospital centres, DC/Virginia, USA Recruitment: May 2003 to October 2009 Maximum follow‐up: 30 days
Participants	45 participants with acute myocardial infarction and Hct < 30% Liberal: n = 21; mean (SD) age = 76.4 (13.5) years Restrictive: n = 24; mean (SD) age = 70.3 (14.3) years
Interventions	Liberal group: transfusion occurred when Hct < 30% to maintain it between 30% and 33% Restrictive group: transfusion occurred when Hct < 24% to maintain it between 24% and 27%
Outcomes	Primary clinical safety measurements: in‐hospital death, recurrent myocardial infarction, new or worsening congestive heart failure
Notes	Trial registration (prospective): NCT00126334 Trial funding: the trial was supported by the Cardiovascular Research Institute of the Washington Hospital Center and received no external funding COI statement by investigators: COI statement not available
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Patients were randomly assigned in a 1:1 ratio to 1 of 2 treatment groups by the coordinating center using consecutively numbered opaque envelopes" (Cooper 2011 p 1108)
Allocation concealment (selection bias)	Low risk	As above
Blinding of participants and personnel (performance bias) Objective outcomes	Low risk	Blinding of personnel for this intervention was not feasible, but in our view, for objective outcomes such as mortality (the primary outcome used within this review), we graded risk of bias as 'low'
Blinding of outcome assessment (detection bias) Objective measures	Low risk	"Patients were followed daily by study personnel during their hospitalization and contacted by telephone at 30 days from randomization. Events were determined by the local study investigator" (Cooper 2011 p 1108) Howver, blinding of mortality (the primary outcome used within this review) is not relevant, and we graded risk of bias as 'low'
Blinding of outcome assessment (detection bias) Subjective measures	Low risk	No data from subjective outcomes (e.g. function)
Incomplete outcome data (attrition bias) All outcomes	Low risk	In‐hospital follow‐up was complete; 3 of 45 participants were lost to follow‐up at 30 days
Selective reporting (reporting bias)	Low risk	Trial registration (prospective): NCT00126334  One outcome planned in the trial registration was not reported, but it was not a main outcome, viz in‐hospital acute renal insufficiency (increase in serum creatinine ≥ 0.5 mg/dL)
Other bias	Low risk	No other biases identified