Risk of venous thromboembolism and efficacy of thromboprophylaxis in hospitalized obese medical patients and in obese patients undergoing bariatric surgery.

BACKGROUND: Obesity is considered a highly prevalent risk factor for venous thromboembolism (VTE) in hospitalized patients. However, recommendations for VTE prophylaxis in obese patients are not clear.
METHODS: To evaluate obesity as a risk factor for VTE in medical and bariatric patients and the efficacy of VTE prophylaxis, we performed a systematic review in MEDLINE, Cochrane Database of Systematic Reviews and LILACS from 1976 to 2006. Evidence was evaluated independently by 2 authors and presented descriptively.
RESULTS: Of the 124 studies found, 87 were excluded based on predefined criteria. There is no consensus among studies, but prospective cohorts show that obesity is associated with a higher risk of VTE in medical patients. There is evidence that the risk of VTE exceeds that attributable to the surgical procedure alone in bariatric surgery. Only 6 studies evaluated prophylactic methods (unfractionated heparin, low molecular weight heparin and sequential compression devices) in obese patients. Although these studies have some methodological flaws, they suggest efficacy of VTE prophylaxis in medical and surgical obese patients.
CONCLUSIONS: Obesity is a risk factor for VTE in obese medical patients and patients undergoing bariatric surgery. Obesity appears to play an adjuvant role for the development of VTE in hospitalized patients with other risk factors. The small number of prospective trials in this population prevents a definite conclusion about the most effective and safe VTE prophylactic method for obese patients. Thus, randomized clinical trials to compare VTE prophylactic methods in obese patients are still highly warranted.