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TITRe2: Restrictive transfusion threshold not superior to liberal strategy after cardiac surgery
After cardiac surgery, use of a restrictive threshold for hemoglobin level in red-cell transfusions was associated with similar morbidity and health care costs compared with a liberal strategy, but increased mortality.
The randomized, controlled, parallel-group TITRe2 study included 2,007 patients older than 16 years who were undergoing nonemergency cardiac surgery at 17 U.K. centers. Patients with a postoperative hemoglobin level less than 9 g/dL were randomly assigned to a restrictive transfusion threshold that targeted a hemoglobin level less than 7.5 g/dL (n = 1,000) or a liberal transfusion threshold that targeted a hemoglobin level less than 9 g/dL (n = 1,003). The liberal-threshold group received a transfusion of 1 unit of red cells immediately after randomization, and an additional unit was administered if the patient’s hemoglobin remained less than 9 g/dL or decreased to less than 9 g/dL during the postoperative hospital stay. The restrictive-threshold group received 1 unit of red cells if the patient’s hemoglobin decreased to less than 7.5 g/dL, and an additional unit was administered if hemoglobin remained less than 7.5 g/dL or decreased to less than 7.5 g/dL during the postoperative hospital stay.
After randomization, the transfusion rate was 53.4% in the restrictive-threshold group vs. 92.2% in the liberal-threshold group. The liberal-threshold group received a median of 2 units of red cells and the restrictive-threshold group received a median of 1 unit.
The primary outcome — serious infection or ischemic events including permanent stroke, MI, infarction of the gut or acute kidney injury within 3 months after randomization — was reported in 35.1% of the restrictive-threshold group vs. 33% of the liberal-threshold group (OR = 1.11; 95% CI, 0.91-1.34). Most primary outcome events occurred while the patient was still hospitalized. The researchers noted no heterogeneity based on subgroups.
The rate of mortality was higher in the restrictive-threshold group (4.2% vs. 2.6%; HR = 1.64; 95% CI, 1-2.67). The 30-day mortality rate was 2.6% in the restrictive-threshold group vs. 1.9% in the liberal-threshold group.
Excluding serious infection and ischemic events, serious postoperative complications occurred in 35.7% of the restrictive-threshold group vs. 34.2% of the liberal-threshold group.
Rates of clinically significant pulmonary complications and mean duration of stay in the ICU or high-dependency unit were similar between the two groups.
In sensitivity analyses, the researchers observed a trend toward increased risk in the restrictive-threshold group when additional acute kidney injury events were included in the primary outcome (OR = 1.2; 95% CI, 1-1.44) and when patients who received transfusions before randomization were not included in the primary outcome analysis (OR = 1.23; 95% CI, 0.97-1.54). There was no significant difference between the groups if the primary outcome was restricted to serious events (OR = 0.99; 95% CI, 0.77-1.27), according to the results.
Health care costs were similar for both strategies. – by Jennifer Byrne
Disclosure: The researchers report no relevant financial disclosures.