Blog | Monday, January 7, 2013

QD: News Every Day--3 studies question the role of blood transfusion

Three studies question the role of blood transfusions for cardiological and gastroenterological conditions, or at least question the thresholds for the procedure.

First, a meta-analysis in Archives of Internal Medicine concluded that blood transfusion or a liberal blood transfusion strategy for myocardial infarction is associated with higher all-cause mortality rates compared with no blood transfusion or a restricted blood transfusion strategy.

Ten studies published between January 1966 and March 2012 revealed the association (18.2% vs. 10.2%; risk ratio [RR], 2.91; 95% confidence interval [CI], 2.46-3.44; P<.001, with a weighted absolute risk increase of 12% and a number needed to harm of 8 (95% CI, 6-17).

Blood transfusion was associated with a higher risk for mortality independent of baseline hemoglobin level, nadir hemoglobin level, and change in hemoglobin level during the hospital stay. It was also significantly associated with a higher risk for subsequent myocardial infarction (RR, 2.04; 95% CI, 1.06-3.93; P=.03).

A journal editor noted, "[U]ntil high-quality randomized trials are performed to test the efficacy of transfusions in the setting of acute myocardial infarction, physicians should transfuse patients only when there is sufficient clinical reason, supported by evidence. Merely having a hematocrit below 27% or 30% should not be sufficient to justify transfusion. In this case, it seems likely that less transfusing may be associated with better outcomes."

Another commentary said, "Do blood transfusions kill more patients with an acute myocardial infarction than anemia? Chatterjee and colleagues would have you believe that they do. We remain unconvinced."

A second study found an association between red blood cell transfusion following nonvariceal upper gastrointestinal bleeding (NVUGIB) and subsequent rebleeding.

Researchers conducted an observational study of a Canadian registry of nearly 1,700 patients with NVUGIB. In the study, 53.7% received transfusions (2.9 +/- 1.6 units of blood), 31.6% had hemodynamic instability, 5.1% fresh blood on rectal examination and 8.6% in the nasogastric tube.

Overall rebleeding and mortality rates were 17.9% and 5.4%, respectively. Red blood cell transfusion within 24 hours of presentation was significantly and independently associated with an increased risk of rebleeding (odds ratio [OR], 1.8; 95% CI; 1.2 to 2.8), but not death (OR, 1.0; 95% CI; 0.6 to 1.8).

Finally, a blood transfusion threshold of 7 g/dL of hemoglobin significantly improved outcomes in patients with acute upper gastrointestinal bleeding compared to 9 g/dL, a study found.

Researchers randomly assigned 444 patients with severe acute upper gastrointestinal bleeding to a restrictive transfusion strategy (transfusion when hemoglobin fell below 7 g/dL with a target range post-transfusion of 7 to 9 g/dL) and 445 patients to a liberal strategy (transfusion when hemoglobin fell below 9 g/dL with a target range post-transfusion of 9 to 11 g/dL). Safety and efficacy of both strategies were compared.

A total of 225 patients assigned to the restrictive strategy did not receive transfusions compared with 65 assigned to the liberal strategy (51% vs. 15%; P less than 0.001). The restrictive-strategy group had a higher survival rate at six weeks compared to the liberal-strategy group (95% vs. 91%; hazard ratio [HR] for death with restrictive strategy, 0.55; 95% CI, 0.33 to 0.92; P=0.02).

Deaths attributed to unsuccessfully controlled bleeding occurred in three patients in the restrictive-strategy group and in 14 patients in the liberal-strategy group (0.7% vs. 3.1%; P=0.01). Complications of treatment were the cause of death in one patient in the restrictive-strategy group and two in the liberal-strategy group. Hemorrhage was controlled and death was due to associated diseases in 19 patients in the restrictive-strategy group and 25 in the liberal-strategy group.

Less bleeding occurred in the restrictive-strategy group compared with the liberal-strategy group (10% vs. 16%; P=0.01), and there were fewer adverse events (40% vs. 48%; P=0.02). Further bleeding was significantly lower with the restrictive strategy group after adjustment for baseline risk factors (HR, 0.68; 95% CI, 0.47 to 0.98). Length of hospital stay was shorter in the restrictive-strategy group than in the liberal-strategy group.

Researchers noted that improvement in survival rates observed with the restrictive transfusion strategy "was probably related to a better control of factors contributing to death, such as further bleeding, the need for rescue therapy, and serious adverse events. All these factors were significantly reduced with the restrictive strategy."