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Risk of hemorrhage from warfarin higher in clinical practice than clinical trials show

Date:
November 26, 2012
Source:
Canadian Medical Association Journal
Summary:
Rates of hemorrhage for older patients on warfarin therapy are much higher than rates reported in clinical trials, found a study published in Canadian Medical Association Journal.
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Rates of hemorrhage for older patients on warfarin therapy are much higher than rates reported in clinical trials, found a study published in CMAJ (Canadian Medical Association Journal).

"The rate of hemorrhage in our study is considerably higher than those reported in randomized controlled trials of warfarin therapy, which have ranged between 1% and 3% per person-year," writes lead author Tara Gomes, Institute for Clinical Evaluative Sciences (ICES), Toronto, with coauthors.

Warfarin, a commonly used blood thinner, is used to treat patients with atrial fibrillation to help prevent stroke and blood clots.

The study looked at 125,195 patients in Ontario aged 66 years or older with atrial fibrillation who started warfarin between Apr. 1, 1997 and Mar. 31, 2008. The overall risk of hemorrhage over the 13-year study period was 3.8% per person-year but was 11.8% in the first 30 days of therapy. For people older than 75 years, the overall risk was 4.6% compared with 2.9% for younger people.

Hemorrhage was defined as major bleeding requiring a visit to the emergency department or admission to hospital. Most admissions to hospital involved gastrointestinal hemorrhages (6785, or 63%). Almost 1 in 5 people (1963, or 18%) admitted to hospital for hemorrhages died in care or within a week after discharge.

"There are currently no large studies offering real-world, population-based estimates of hemorrhage rates among patients taking warfarin, which are needed for future comparisons with new anticoagulant agents once they are widely used in routine clinical practice," the authors write.


Story Source:

The above post is reprinted from materials provided by Canadian Medical Association Journal. Note: Materials may be edited for content and length.


Journal Reference:

  1. Tara Gomes, Muhammad M. Mamdani, Anne M. Holbrook, J. Michael Paterson, Chelsea Hellings, David N. Juurlink. Rates of hemorrhage during warfarin therapy for atrial fibrillation. CMAJ, 2012 DOI: 10.1503/cmaj.121218

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Canadian Medical Association Journal. "Risk of hemorrhage from warfarin higher in clinical practice than clinical trials show." ScienceDaily. ScienceDaily, 26 November 2012. <www.sciencedaily.com/releases/2012/11/121126131120.htm>.
Canadian Medical Association Journal. (2012, November 26). Risk of hemorrhage from warfarin higher in clinical practice than clinical trials show. ScienceDaily. Retrieved July 1, 2015 from www.sciencedaily.com/releases/2012/11/121126131120.htm
Canadian Medical Association Journal. "Risk of hemorrhage from warfarin higher in clinical practice than clinical trials show." ScienceDaily. www.sciencedaily.com/releases/2012/11/121126131120.htm (accessed July 1, 2015).

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