Vitamin K Antagonists Compared to Low-Molecular-Weight Heparins for Treatment of Cancer-Associated Venous Thromboembolism: An Observational Study in Routine Clinical Practice. An Observational Study in Routine Clinical Practice.

Since several trials have demonstrated that low-molecular-weight-heparin (LMWH) is superior to vitamin K antagonist (VKA) in preventing recurrent venous thromboembolism (VTE) in patients with cancer-associated VTE, guidelines now recommend LMWH monotherapy in this setting. We evaluated whether this shift resulted in improved outcomes in routine clinical practice. We performed a cohort study of consecutive patients with cancer-associated VTE during 2001 and 2010. We compared the risks for recurrent VTE, major bleeding and mortality between patients diagnosed before and after 2008 during a 6-month routine follow-up. A total of 381 patients were included, of which 234 (61.4%) were diagnosed before 2008. Before 2008, 23% of the patients were treated with LMWH; thereafter, this percentage was higher: 67%. The 6-month incidence for recurrent VTE was 8.6% in patients diagnosed before 2008 versus 7.5% for patients diagnosed after 2008 (risk difference [RD]: -1.1%; 95% confidence interval [CI]: -6.3, 5.3). The respective risks for major bleeding were 6.4 versus 4.8% (RD: -1.6%; 95% CI: -3.8 to 5.8), and 39.7 versus 41.5% (RD: 1.8%; 95% CI: -8.8, 12) for overall mortality. The mean time in therapeutic range (TTR) of patients treated with VKA was 61%. Despite a clear shift toward LMWH as agent of choice for cancer-associated VTE, we did not observe a clear improvement in terms of recurrent VTE and bleeding complications.