(HealthDay News) – There is insufficient evidence to support the use of intravascular filters or augmented dosing of anti-clotting medication to prevent venous thromboembolism (VTE) in patients undergoing bariatric surgery, according to a review published online May 29 in JAMA Surgery.

Daniel J. Brotman, MD, from Johns Hopkins University in Baltimore, and colleagues reviewed the literature for primary studies that had at least two different interventions to compare the effectiveness and safety of pharmacologic and mechanical strategies to prevent VTE in patients undergoing bariatric surgery.

The researchers identified eight studies involving pharmacologic strategies and five studies involving filter placement. There were no randomized studies. One study showed that low-molecular-weight heparin was significantly more effective than unfractionated heparin in preventing VTE but there was no significant difference in bleeding. Another study found that prolonged therapy with enoxaparin sodium (after discharge) may have prevented VTE better than inpatient treatment only. The evidence was insufficient that filters reduce the risk of pulmonary embolism, with a point estimate suggesting increased rates with filters (pooled relative risk [RR], 1.21; P=0.62;). Low-grade evidence suggested that filters are associated with higher mortality (pooled RR, 4.30) and higher deep vein thrombosis rates (pooled RR, 2.94). The evidence was insufficient to support that augmented subcutaneous enoxaparin doses (>40mg daily or 30mg twice daily) were more efficacious than standard dosing, with a trend toward increased bleeding.

“Overall, our findings support the use of ‘standard’ doses of pharmacotherapy as prophylaxis for patients undergoing bariatric surgery, consistent with current American College of Chest Physicians guidelines, which do not distinguish between patients undergoing bariatric surgery and those undergoing other types of abdominal surgery,” the authors write. “We found no evidence to support filter placement as prophylaxis in patients undergoing bariatric surgery, with a trend toward higher deep vein thrombosis rates and higher mortality in patients receiving filters.”

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