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 A Systematic Review and Meta-Analysis of Anticoagulation Examined

May 16, 2011
Contact: Jill Goodwin, 312-334-2308
Media invited to attend – contact above with credentials
Interviews available upon request
Anticoagulation for calf deep venous thrombosis may decrease outcomes for pulmonary embolus
CHICAGO— Researchers from the Dartmouth-Hitchcock Medical Center and the Dartmouth Institute for Health Policy and Clinical Practice in Lebanon, N.H. have found that anticoagulation for calf deep venous thrombosis (CDVT) may decrease clinically important outcomes such as pulmonary embolus (PE) and clot propagation. Their findings were revealed today at the 65th Vascular Annual Meeting® presented by the Society for Vascular Surgery®.

According to Randall R. De Martino, MD, from the section of vascular surgery at Dartmouth-Hitchcock Medical Center, a systematic review was performed utilizing Medline, the Cochrane Library, and meeting abstracts. To be included in their review and analysis, all studies had patients with confirmed CDVT diagnosed by ultrasound or venogram. Additionally, studies had to compare patients treated with anticoagulation (vitamin K antagonist or heparin) for 30 or more days to controls (not anticoagulated) with a minimum one month follow-up. Their primary study outcome was PE and secondary outcomes were clot propagation, post-thrombotic syndrome, mortality, and bleeding. The data from qualifying articles was then extracted by independent reviewers and quality assessment was performed using standardized scales. A meta-analysis was performed by generating pooled odds ratios with subgroup and sensitivity analyses.
“We screened 2,328 studies and reviewed 148 full text articles,” said Dr. De Martino. “Eight studies met our selection criteria; 2 randomized control trials and 6 cohort. This yielded 126 anticoagulated patients and 378 controls for analysis. Notably, most studies were of poor methodological quality and did not report all outcomes. Rates of PE (OR 0.12, 95 percent CI 0.02-0.77, p=0.03) and clot propagation (OR 0.29, 95 percent CI 0.14-0.62, p=0.04) were significantly lower in patients treated with anticoagulation. Due to heterogeneity, results for bleeding complications and mortality could not be pooled, but favored controls or anticoagulation respectively. There were sparse data on post-thrombotic syndrome available.”

Dr. De Martino noted that this study was limited by the quality of present studies in the literature. The results suggest that anticoagulation for CDVT may decrease clinically important outcomes such as PE and clot propagation.  Yet, “Treatment-related complications have been poorly documented. This makes determining the benefits and harms of treatment difficult,” said Dr. De Martino. “More rigorous studies can improve the quality evidence for treatment for calf vein DVT.”

About the Society for Vascular Surgery
The Society for Vascular Surgery® (SVS) is a not-for-profit professional medical society, composed primarily of vascular surgeons, that seeks to advance excellence and innovation in vascular health through education, advocacy, research, and public awareness. SVS is the national advocate for 3,370 specialty-trained vascular surgeons and other medical professionals who are dedicated to the prevention and cure of vascular disease. Visit its Web site at® and follow SVS on Twitter by searching for VascularHealth or at

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