The threshold at which postoperative red blood cell transfusion is warranted for patients with cardiac disease remains controversial. While the hazards associated with transfusions are well known to the modern-day intensivist, some have proposed that transfusions improve functional recovery for elderly surgical patients, and prevent cardiovascular events. Jeffrey Carson, MD, and the Functional Outcomes in Cardiovascular Patients Undergoing Surgical Hip Repair (FOCUS) investigators conducted a randomized trial to test the hypothesis that morbidity and mortality rates would be reduced when high-risk surgical patients (elective hip surgery) were transfused to a hemoglobin level of 10 g/dL (liberal strategy group) versus 8 g/dL (restrictive strategy group).
Forty-seven clinical sites throughout North Americaenrolled 2,016 patients. Inclusion criteria (and the definition of high-risk) included elective surgery patients 50 years or older with active cardiac disease or at least one independent risk factor for cardiovascular disease. Block randomized was employed, and while clinicians and patients were not blinded to group assignments, investigators who classified cardiovascular outcomes were blinded. The primary outcome was death or inability to walk 10 feet across a room without assistance by 60 days. Secondary outcomes included in-hospital myocardial infarction, unstable angina, or death for any reason. Additional measures for morbidity also were assessed.
Rates of death or an inability to walk without assistance at 60-day follow-up were not statistically significantly different between the restrictive (35.2%) and liberal strategy group (34.7%, P=0.90). There were no significant differences between groups regarding functional outcomes, including activities of daily living and fatigue.
The results from this study are consistent with the Transfusion Requirements in Critical Care trial, although increased rates of myocardial infarction or congestive heart failure were not observed in the liberal strategy group. It should be noted that before surgery, the restrictive strategy group had more transfusions than the liberal group, but this was not statistically significant (P=0.07), and the mean hemoglobin level was 11.3 in both groups before surgery. Furthermore, the difference between a hemoglobin level of 8 vs. 10 may or may not be clinically significant. This well-designed and methodologically rigorous study provides additional evidence to support a restrictive transfusion strategy in surgical patients, even when cardiac risk factors are present.
CarsonJL, et al. for the FOCUS Investigators. Liberal or restrictive transfusion in high-risk patients after hip surgery. N Engl J Med 2011; epub ahead of print.
Concise Critical Appraisal is a regular feature authored by SCCM member Samuel M. Galvagno Jr., DO. Each installment highlights journal articles most relevant to the critical care practitioner.