Hemoglobin-based transfusion strategies for cardiovascular and other diseases: restrictive, liberal, or neither?

A "restrictive" red blood cell transfusion threshold, a hemoglobin concentration <7 to 8 g/dL, has long been recommended for most hospitalized patients including anemic patients with stable cardiovascular disease (CVD). Although no threshold recommendation is given for acute coronary syndromes (ACSs), recent evidence suggests that "liberal" rather than "restrictive" transfusion strategies are associated with significantly improved safety for hospitalized patients with stable CVD and/or ACS. This finding suggests that previously available data were misinterpreted. Conclusions drawn from earlier transfusion trigger trials have been confounded by unintentional trial design and analysis flaws that have contributed to erroneous recommendations regarding the safety of a restrictive threshold. Subsequently, these conclusions have been incorporated into widely accepted guidelines and clinical practice. Management with a restrictive vs liberal transfusion strategy (<10 g/dL) increases the risk of new-onset ACS in patients with CVD by ∼2%. We estimate that since 2019, using hospital databases and a recent meta-analysis, this practice may have resulted in ∼700 excess ACS events per year in orthopedic surgical patients. Given these findings, transfusion practices in other clinical conditions, particularly those derived from similar transfusion trigger trials, should be questioned. Restrictive and liberal transfusion policies merit a general reconsideration. Rather than a single numerical transfusion trigger, transfusion therapy should be personalized. Consideration of an individual patient's age, clinical status, and comorbidities is integral to transfusing. To avoid making similar errors, future trials of transfusion therapy should determine common practices before study inception and incorporate them as a usual-care "control" comparator arm into the trial design. Such studies should more reliably improve current transfusion practice.