Background: Venous thromboembolism (VTE) is the third most common vascular disease. Medical inpatients, long-term care residents, persons with minor injuries, and long-distance travelers are at increased risk. Objective: These evidence-based guidelines from the American Society of Hematology (ASH) intend to support patients, clinicians, and others in decisions about preventing VTE in these groups. Methods: ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline-development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and adult patients. The Grading of Recommendations Assessment, Development and Evaluation approach was used to assess evidence and make recommendations, which were subject to public comment. Results: The panel agreed on 19 recommendations for acutely ill and critically ill medical inpatients, people in long-term care facilities, outpatients with minor injuries, and long-distance travelers. Conclusions: Strong recommendations included provision of pharmacological VTE prophylaxis in acutely or critically ill inpatients at acceptable bleeding risk, use of mechanical prophylaxis when bleeding risk is unacceptable, against the use of direct oral anticoagulants during hospitalization, and against extending pharmacological prophylaxis after hospital discharge. Conditional recommendations included not to use VTE prophylaxis routinely in long-term care patients or outpatients with minor VTE risk factors. The panel conditionally recommended use of graduated compression stockings or low-molecular-weight heparin in long-distance travelers only if they are at high risk for VTE.

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Odds ratios and their 95% confidence intervals (95% CI) were cal- open-access paper. doi:10.3324/haematol.2013 Recent studies suggest that leukocytes and erythrocytes play a role in coagulation. However, whether leukocytes, erythrocytes and other hematologic variables are associated with risk of venous thrombosis is not well known. To study this, we used data from 2473 patients with venous thrombosis and 2935 controls. The variables assessed were: total leukocytes, granulocytes, lymphocytes, monocytes, hematocrit, hemoglobin, erythrocytes and red cell indices (mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration and red cell distribution width). We found a strong dose-response relation for higher red cell distribution width and monocyte count with risk of venous thrombosis, with odds ratios of 3.1 (95% confidence interval, 2.0-4.8) and 2.8 (95% confidence interval, 1.3-5.8), respectively, after adjustment for age, sex, C-reactive protein level, malignancy and co-morbidities. Monocyte count and red cell distribution width were associated with venous thrombosis even within reference ranges. A low monocyte count (<0.12x10 9 /L) was associated with a lower risk of venous thrombosis after full adjustment (odds ratios 0.6; 95% confidence interval, 0.4-0.8). In summary, high red cell distribution width and blood monocyte count, two parameters that are inexpensive and easily obtainable, were clearly associated with an increased risk of venous thrombosis. Future studies should evaluate the underlying mechanism and the use of these variables in prediction models for first and recurrent thrombosis. ©2013 Ferrata Storti Foundation. This is an Hematologic variables and venous thrombosis: red cell distribution width and blood monocyte count are associated with an increased risk