Obesity and deep vein thrombosis

Obesity and Deep vein thrombosis

Obesity is measured as body mass index above 30. The body mass index (BMI) is measured as weight in kilograms divided by the square of height in meter. Obesity is associated with venous thromboembolism (VTE). Body mass index is a marker of excess weight and correlates well with body fat content in adults. Body mass index fails to consider the importance of the distribution of body fat. All measurements of obesity are predictors of the risk for VTE. Positive associations were found between VTE and body weight, body mass index, waist circumference, hip circumference, and total body fat mass (1). The fact is that the fat distribution is not uniform in all the people and so there are different shapes of individuals. Basically obesity is differentiated as central or peripheral depending on the degree of fat accumulation in the central part of the body or extremities. Studies were done to find out the differences in risk associated with these types of fat distribution. The distribution of body fat predicts the risk of arterial thrombotic events, such as coronary heart disease (CHD). Central obesity is a better predictor of CHD than general obesity as measured with BMI.  Central obesity is measured as waist circumference or waist-to-hip ratio. It is important note that peripheral obesity is not a predictor of coronary heart disease. The peripheral obesity is measured as hip circumference (2,3). One study evaluated the association between VTE and central obesity in men and found that a waist circumference >100 cm was associated with a higher risk of VTE than a waist circumference  less than 100 cm (4).It is also important know the benefit of thrombo-prophylaxis in obese people who are undergoing major surgeries such as total knee arthroplasty. In a case-control study, they studied (130, 463) patient with and patients without acute VTE (within 9 days of surgery) and BMI ranging from 17 to 61.  Multivariable logistic regression was used to analyze risk factors for postoperative VTE, adjusted for age and gender. Thromboprophylaxis was LMWH in 284 (48%), warfarin in 189 (32%), both in 55 (10%), and mechanical prophylaxis alone in 120 (20%). Overall, 77% ambulated on day 1 or 2 after surgery. Severe obesity was not a significant independent predictor for VTE and did not modify the beneficial effect of FDA-approved pharmacological thromboprophylaxis. Bilateral TKA and failure to ambulate by the second day after surgery were significant risk factors (5). 

References:

1.   Knut H. Borch, Sigrid K. Brækkan, Ellisiv B. Mathiesen, Inger Njølstad, Tom Wilsgaard, Jan Størmer, and John-Bjarne Hansen. Anthropometric Measures of Obesity and Risk of Venous Thromboembolism: The Tromsø Study. Arterioscler Thromb Vasc Biol. 2010;30:121-12.   

2.   Canoy D, Boekholdt SM, Wareham N, Luben R, Welch A, Bingham S, Buchan I, Day N, Khaw KT. Body fat distribution and risk of coronary heart disease in men and women in the European Prospective Investigation Into Cancer and Nutrition in Norfolk cohort: a population-based prospective study. Circulation. 2007; 116: 2933–2943. 

3.   Yang L, Kuper H, Weiderpass E. Anthropometric characteristics as predictors of coronary heart disease in women. J Intern Med. 2008; 264: 39–49 

4.   Hansson PO, Eriksson H, Welin L, Svardsudd K, Wilhelmsen L. Smoking and abdominal obesity: risk factors for venous thromboembolism among middle-aged men: “the study of men born in 1913.” Arch Intern Med. 1999; 159: 1886–1890.

5.   Sadeghi B, Romano PS, Maynard G, Strater AL, Hensley L, Cerese J, White RH. Mechanical and suboptimal pharmacologic prophylaxis and delayed mobilization but not morbid obesity are associated with venous thromboembolism after total knee arthroplasty: A case-control study. J Hosp Med. 2012 Oct 5. doi: 10.1002/jhm.1962. [Epub ahead of print]