For Elective CABG, Perioperative Hematocrit Target of ≥ 24% (Compared with ≥ 30%) Reduces Blood Transfusion Rate and May Not Increase Morbidity

DynaMed Weekly Update - Volume 5, Issue 42

The decision about when to give blood transfusions is complex, requiring a careful assessment of risks and benefits. The TRACS trial compared the effects of giving blood transfusions perioperatively using a target of maintaining hematocrit at ≥ 24% vs. ≥ 30% in 502 patients having an elective coronary artery bypass graft (CABG). Patients were evaluated for a composite outcome which included 30-day all-cause mortality and severe morbidity (cardiogenic shock, acute respiratory distress syndrome, or acute renal injury requiring dialysis or hemofiltration) during hospital stay. The trial was designed to see if limiting blood transfusions with a goal of maintaining the hematocrit ≥ 24% was not inferior to the strategy of using transfusions to keep the hematocrit ≥ 30%. Using a target hematocrit of ≥ 24% reduced the rate of transfusion (47% vs. 78%, p < 0.001, NNT 4) (

level 1 [likely reliable] evidence). There were no statistically significant differences in the composite outcome (11% vs. 10%, which met the pre-specified non-inferiority margin) (level 2 [mid-level] evidence), although there were nonsignificant absolute increases in mortality of 1% and in cardiogenic shock of 4% in the lower target group. There were no significant differences in complications, severe bleeding, or hospital stay (JAMA 2010 Oct 13;304(14):1559).

For more information, see the Coronary artery bypass graft (CABG) topic in DynaMed.