Foss 2009.

Study characteristics
Methods	Design: RCT, parallel, single‐site trial Setting: university teaching hospital, Denmark Recruitment: February 2004 to July 2006 Maximum follow‐up: 30 days (for mortality); ambulatory capacity (the primary outcome) was assessed at 3 days
Participants	120 hip fracture participants were randomly allocated: Liberal group: n = 60; M/F = 14/46; mean (SD) age = 81 (6.8) years Restrictive group: n = 60; M/F = 14/46; mean (SD) age = 81 (7.3) years
Interventions	Liberal group: received packed RBCs when Hb dropped to < 10.0 g/dL Restrictive group: received packed RBCs when Hb dropped to < 8.0 g/dL
Outcomes	Ambulatory capacity (measured by Cumulated Ambulatory Score), mortality, length of stay, cardiac complications, infectious complications
Notes	Trial registration: NCT00162617 Trial funding: received financial support from IMK‐Almene fond (Denmark) COI statement by investigators: "the authors have no conflicts of interest" (Foss 2009 p 227)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"The randomization was done via a computer generated list by a person not affiliated with the project" (Foss 2009 p 228)
Allocation concealment (selection bias)	Low risk	"Upon inclusion, the sealed envelope, containing the transfusion threshold and with the patient’s study number on it, was placed in the patient charts next to the transfusion papers concealing the allocation to both the patient and the physiotherapists conducting the ambulation assessments, making the study double‐blind" (Foss 2009 p 228)
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	Blinding of mortality (the primary outcome used within this review) is not relevant, and we graded risk of bias as 'low'   "....30‐day mortality were registered, the latter established via the Danish civil registry" (Foss 2009 p 229)
Blinding of outcome assessment (detection bias) Subjective measures	Low risk	The physiotherapist who performed ambulation assessment was blinded ".... concealing the allocation to both the patient and the physiotherapists conducting the ambulation assessments, making the study double‐blind" (Foss 2009 p 228)
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	13 of 100 participants did not have ambulation assessment (54/60 included in per‐protocol analysis of liberal transfusion; 53/60 in restrictive transfusion)
Selective reporting (reporting bias)	Low risk	Trial was prospectively registered (NCT00162617). No reporting bias was apparent
Other bias	Low risk	No other biases were apparent