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Possible risk factors identified for VTE during stem cell transplant
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Prior venous thromboembolism and development of graft-versus-host disease were significant risk factors for the development of venous thromboembolism in patients undergoing hematopoeitic stem cell transplant, according to recent data.
Researchers from the University of Texas Southwestern Medical Center and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University analyzed risk factors for venous thromboembolism and for bleeding among 1,514 patients who did not receive venous thromboembolism prophylaxis prior to their inpatient stem cell transplants.
Between admission and day 180, 70 patients experienced 75 symptomatic venous thromboembolic events, for an incidence rate of 4.9%. None of the venous thromboembolic events were fatal. On multivariate analysis, a prior venous thromboembolism (OR=2.9; 95% CI, 1.3-6.6) and development of GVH disease (OR=2.4; 95% CI, 1.4-4.0) were significantly associated with venous thromboembolism development.
Clinically significant bleeding episodes occurred in 230 patients, for an incidence rate of 15.2%. Fifty-five patients died from bleeding, for a case-fatality rate of 24%. Initiation of anticoagulation therapy during the first 180 days was the strongest predictor of bleeding (OR=3.1; 95% CI, 1.8-5.5). Other risk factors were nonwhite race (OR=1.3; 95% CI, 1.1-1.6) and GVH disease (OR=2.4; 95% CI, 1.8-3.3), according to the researchers. – by Emily Shafer
Blood. 2008;112:504-510.
There is currently a trend to initiate routine venous thrombosis prophylaxis for all non-surgical patients, but the data here suggest that bleeding is more of a problem than thrombosis in stem cell transplant recipients. In this study, no deaths were attributable to venous thrombosis; however, there was a 3.6% rate of death attributable to bleeding. The limitations of the retrospective design, however, mean that this is not the definitive study. The bottom line is that the use of thrombosis prophylaxis is still an individualized decision, and there are situations in which prophylactic anticoagulation is worthwhile. We need more data about the true risk of thrombosis — from autopsy studies, for example — before making standard recommendations for prophylactic anticoagulation. These data show that bleeding is a risk, but they do not exclude the possibility that occult thrombosis could be a problem.
The data demonstrate that anticoagulation therapy is a risk factor for bleeding. In this group of patients, who have received high-dose chemoradiation or have very low platelet counts, bleeding appears to be a more important concern than venous thrombosis. However, we know from other studies that the frequency of death related to occult pulmonary emboli found at autopsy is significantly underestimated. An estimated 70% to 80% of clinically significant pulmonary emboli are not diagnosed before death. The symptoms, such as shortness of breath, are often not recognized to be due to pulmonary embolism because of other problems such as pneumonia.
If, indeed, there is a high rate of occult pulmonary embolism, the risk-benefit ratio could be in favor of prophylactic anticoagulation. With the available data, the researchers conclude, and I agree, that since they saw fatal bleeding, and anticoagulation therapy is a risk factor for bleeding, the risk-benefit ratio is not in favor of routine prophylactic anticoagulation. However, when faced with a patient with a major previous thrombotic event, then I think most of us would still offer some form of prophylactic anticoagulation.
– Nigel Key, MD
HemOnc Today Editorial Board member