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American Journal of Medicine
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This Figure begins to address some of the emerging data with these new anticoagulant agents. There is a need for Cochrane-level systematic meta-analyses and evidence-based reviews (looking outside of clinical trial populations, etc.) to support a better understanding of the comparative effectiveness of these agents. Figure 11 refers to an evidence-based synthesis program put together by the Veterans Administration (VA) Health Administration in the United States. One of the key questions this program tackled was whether for patients with VTE there are differential effects of the newer oral anticoagulants versus warfarin or LMWH on recurrent thromboembolism, mortality, health related quality of life, and patient treatment experience.[6] To answer these questions, these investigators looked at three studies that included a factor Xa inhibitor as well as the direct thrombin inhibitor dabigatran.
The review included 8477 patients. All three studies compared the new anticoagulants to a dose of warfarin that was adjusted to achieve a median time-in-treatment range (TTR) of 60%. As a physician who deals with warfarin on a daily basis, I would state that this is not the best TTR, but given all of the difficulties with warfarin, the TTR that we are able to achieve in clinical practice is often around 60%. In other words, although the TTR in these three studies is not 70 – 72%, it still clearly represents what is seen in clinical practice.
In addition, the mean age across these studies was in the range of 50 to 55 years. Another very important point for clinicians to appreciate is the effect of age differences across these different indications for anticoagulant therapy:
This means that the different populations tend to center on the decades of 70-, 60-, and 50-year-olds, respectively, and it is important to be able to interpret the different results in the different populations in an intelligent fashion regarding the safety of these different agents. Hylek E. Am J Med 2013; published on-line at http://education.amjmed.com/00000.
[6] Adam SS, McDuffie JR, Ortel TL, Nagi A, Williams JW Jr. Comparative effectiveness of warfarin and newer oral anticoagulants for the long-term prevention and treatment of arterial and venous thromboembolism. VA-ESP Project #09-010; Washington (DC): Department of Veterans Affairs; 2012.