| Methods |
Randomised clinical trial |
| Participants |
Participants older than 16 years of age who were undergoing nonemergency cardiac surgery with haemoglobin level below 9 g/dL
Liberal: n = 1003; median age (interquartile range) = 70.8, (64.1 to 76.7) years Restrictive: n = 1000; median age (interquartile range) = 69.9 (63.1 to 76.0) years
|
| Interventions |
The liberal transfusion threshold group received transfusion when the haemoglobin level was < 9 g/dL, and the restrictive transfusion threshold group received transfusion when the haemoglobin level was less than 7.5 g/dL. |
| Outcomes |
The primary outcome was a composite of a serious infection (sepsis or wound infection) or an ischaemic event (permanent stroke, myocardial infarction, infarction of the gut, or acute kidney injury) within 3 months after randomisation. Secondary outcomes included units transfused, infection, ischaemic events, acute kidney injury, hospital stay and ICU stay, and cost. |
| Notes |
‐ |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
The use of random sequence generation was not stated. |
| Allocation concealment (selection bias) |
Low risk |
The trial used an internet‐based system that concealed assignments and used cohort minimisation to balance assignments according to centre and type of surgery. |
| Blinding of participants and personnel (performance bias)
All outcomes |
Unclear risk |
Physicians and nurses were aware of the group assignments. "We intended participants to be unaware of the group assignments and tested our success in keeping the study groups blinded by asking the patients if they were aware of the group they were in." At discharge 15.1% of patients believed they knew treatment and 75.6% were correct. |
| Blinding of outcome assessment (detection bias)
All outcomes |
Low risk |
Outcomes were adjudicated. |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
The was a low loss to follow up. |
| Selective reporting (reporting bias) |
Low risk |
No reporting bias was apparent. |
| Other bias |
Low risk |
No other biases were apparent. |
