Transfusions Linked to Venous, Arterial Thrombotic Events in Cancer Patients CME

December 2, 2008 - In patients hospitalized with cancer, red blood cell (RBC) and platelet transfusions are associated with an increased risk for venous and arterial thrombotic events, according to the results of a retrospective cohort study reported in the November 24 issue of the Archives of Internal Medicine.

"Anemia is frequent in patients with cancer, but there are concerns regarding treatment with erythropoiesis-stimulating agents," write Alok A. Khorana, MD, from the University of Rochester in Rochester, New York, and colleagues. "Blood transfusions are commonly used as an alternative, but with little data regarding outcomes."

Using the discharge database of the University HealthSystem Consortium, the investigators examined the associations between transfusions and venous thromboembolism, arterial thromboembolism, and mortality rates in hospitalized patients with cancer. The study sample included 504,208 hospitalizations of cancer patients at 60 US medical centers between 1995 and 2003.

Of the patients examined in this analysis, 70,542 (14.0%) received at least 1 RBC transfusion and 15,237 (3.0%) received at least 1 platelet transfusion. Venous thromboembolism occurred in 7.2% of patients receiving RBC transfusions and arterial thromboembolism in 5.2%. These rates were significantly greater than the rates of 3.8% and 3.1%, respectively, seen in patients who did not receive transfusions (P < .001).

An increased risk for venous thromboembolism was independently linked to RBC transfusion (odds ratio [OR], 1.60; 95% confidence interval [CI], 1.53 - 1.67) and platelet transfusion (OR, 1.20; 95% CI, 1.11 - 1.29), based on multivariate analysis. Similar results were seen with arterial thromboembolism (OR for RBC transfusion, 1.53; 95% CI, 1.46 - 1.61; and OR for platelet transfusion, 1.55; 95% CI, 1.40 - 1.71; P < .001 for each). Transfusions were also associated with a higher risk for death during hospitalization (OR for RBC transfusion, 1.34; 95% CI, 1.29 - 1.38; and OR for platelet transfusion, 2.40; 2.27 - 2.52; P < .001).

"Both RBC and platelet transfusions are associated with increased risks of venous and arterial thrombotic events and mortality in hospitalized patients with cancer," the study authors write. "Further investigation is necessary to determine whether this relationship is causal."

Limitations of this study include reliance on administrative coding; inability to identify patients concomitantly receiving erythropoiesis-stimulating agents as part of outpatient therapy, which is a potential confounding factor; lack of data regarding compliance with appropriate thromboprophylaxis; inability to determine the time of administration of transfusion in relationship to the development of thromboembolic events or to identify patients admitted with venous thromboembolism who subsequently needed transfusions; and the possibility that anemia is a marker for aggressive tumor biology, more intensive chemotherapy, or "sicker" patients.

"Controversy exists regarding the treatment of anemia in cancer with ESAs [erythropoiesis-stimulating agents] because of potential adverse effects, including thromboembolism and worsened survival," the study authors write. "Data presented herein suggest caution in using transfusions as an alternative to ESAs because these may carry a similar risk of adverse thrombotic and survival outcomes. These findings suggest that rigorous studies evaluating the risks and benefits of blood transfusion in patients with cancer are necessary."

Arch Intern Med. 2008;168:2377-2381.