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Warfarin transition appears tolerable in patients with cancer-associated thrombosis
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ORLANDO, Fla. — Switching to warfarin compared with remaining on low–molecular-weight heparin did not appear associated with increased recurrent venous thromboembolism, major bleeding or total bleeding among patients with cancer-associated thrombosis, according to study results presented at the ASH Annual Meeting and Exposition.
Further, warfarin acted as an acceptable alternative anticoagulant in patients who could not tolerate long-term treatment with low–molecular-weight heparin (LMWH).
“LMWH is considered to be the anticoagulation of choice for the treatment of cancer-associated thrombosis,” Chatree Chai-Adisaksopha, MD, clinical fellow at McMaster University in Hamilton, Ontario, said during a press conference. “This is based on the results of the CLOT trial, which found that dalteparin [Fragmin, Pfizer] significantly reduced the risk for recurrent VTE compared with warfarin. However, the data regarding the choice of anticoagulation after 6 months of treatment remains unclear.”
Chai-Adisaksopha and colleagues accessed the RIETE registry to identify 1,502 consecutive patients with cancer-associated thrombosis who completed 6 months of LMWH. They divided patients into two groups: those who continued to receive LMWH (n = 763) after 6 months and those who switched to warfarin (n = 739).
Incidence of recurrent VTE, major bleeding and total bleeding served as the primary endpoints.
The median follow-up was 11 months (interquartile range, 7.4-18,1).
The researchers did not observe any significant differences in terms of recurrent VTE (HR = 0.7; 95% CI, 0.46-1.07). Recurrent VTE occurred in 55 patients (7.2%) who continued to receive LMWH and 44 patients (6%) who switched to warfarin.
Both groups had similar instances of major bleeding (2.6% vs. 2.7%; HR = 1.05; 95% CI, 0.79-1.55) and total bleeding (6.7% vs. 7%; HR = 0.92; 95% CI, 0.62-1.37).
“Switching to warfarin does not increase the risk for VTE or major bleeding after 6 months on anticoagulation treatment,” Chai-Adisaksopha said. “However, our study may have some confounding factors, and these results need to be confirmed by a prospective study.” – by Cameron Kelsall
Reference:
Chai-Adisaksopha C, et al. Abstract 430. Presented at: ASH Annual Meeting and Exposition; Dec. 5-8, 2015; Orlando, Fla.
Disclosure: One study researcher reports consultant roles and advisory committee memberships with Bayer, Boehringer Ingelheim, Daiichi Sankyo and Sanofi.
Perspective
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Annemarie Fogerty, MD
The CLOT trial established low–molecular-weight heparin (LMWH) as the standard of care in patients, and this paper doesn’t change that in the upfront setting, because patients are not transitioning to warfarin until after 6 months. What it does is identify a population of people who, after 6 months, are sick of shots and can be candidates for a warfarin transition. The primary problem with warfarin — even in the earlier trials — was the difficulty maintaining a therapeutic international normalized ratio in patients who were actively being treated with chemotherapy, and with issues of nausea and vomiting in patients having difficulty taking a drug and throwing up after. If you are removed from those first 6 months, when the therapy is often most intense, then warfarin will be successful due to a higher likelihood of maintaining a therapeutic INR.
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