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VTE prevention may be unnecessary in bariatric surgery patients
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The literature suggests that measures should be carried out to prevent venous thromboembolism in patients undergoing bariatric surgery. However, data from a recent analysis of several studies demonstrate there is no conclusive evidence to support their use.
Daniel J. Brotman, MD, associate professor of medicine and director of the hospitalist program at The Johns Hopkins Hospital, and colleagues wrote that strategies to prevent VTE in patients undergoing bariatric surgery can include augmented dosing of pharmacotherapy (ie, enoxaparin sodium administered >40 mg daily or 30 mg twice daily) and the placement of inferior vena cava filters before surgery.
In a systematic review and meta-analysis, Brotman and colleagues assessed the efficacy and safety of these methods. They included 13 articles: five involved patients with and without filters and eight included patients receiving different pharmacologic therapies.
Brotman and colleagues report that none of the selected studies randomly assigned patients to receive various interventions. However, one study reported low–molecular-weight heparin was superior to unfractionated heparin in the prevention of VTE (0.25% vs. 0.68%, P<.001), according to researchers. This particular study also noted no significant differences in bleeding, they added.
Another study suggested that continued postoperative enoxaparin sodium therapy might be more effective in preventing VTE compared with inpatient treatment, they wrote.
Additional data indicate a lack of evidence to support the hypothesis that vena cava filters reduced the risk for pulmonary embolism. Further, they suggested increased rates with filters (RR=1.21; 95% CI, 0.57-2.56), researchers wrote.
Moreover, Brotman and colleagues wrote that low-grade evidence suggested filters were linked to a greater risk for mortality (RR=4.30; 95% CI, 1.60-11.54), in addition to an increased risk for deep vein thrombosis (RR=2.94; 95% CI, 1.35-6.38).
“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,” the researchers wrote. “… We note that, despite the patient population, which might be assumed to be at particularly high risk of postoperative VTE because of their body habitus, rates of thrombosis and mortality were reassuringly low.”
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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Bruce M. Wolfe, MD
From the research standpoint, the incidence or frequency of venous thromboembolism, particularly fatal pulmonary embolism, is so low that it is exceedingly difficult to study. To do a randomized trial that is adequately powered to give definitive answers as to how to prevent it is very difficult because the study has to be large due to the low incidence. The researchers highlight various papers due to the fact that pulmonary embolism is generally number two on the list of causes of death when uncommon deaths do occur as a result of bariatric surgery.
It’s a frightening potential risk and deserves the attention it gets. However, there is no more than 1 death out of 1,000 surgeries due to pulmonary embolism.
The researchers found that one study suggested low-molecular-weight heparin is more efficacious than unfractionated heparin in preventing VTE. However, I’m not convinced that it’s a matter of which drug rather than dose.
Another paper found that if you continue the prophylaxis beyond the hospitalization, this may be a way to prevent VTE better compared with inpatient treatment alone. That’s an interesting and challenging observation because of the logistics of continuing an injectable treatment for the people who have left the hospital. It is certainly complicated by the time you teach the people how to do their own injections.
However, there is evidence that the risk of VTE lasts for as long as 90 days, so that’s one of the findings that it did seem to be impressive. Otherwise, they weren’t able definitively prove much about the effectiveness and safety strategies to prevent VTE in patients undergoing bariatric surgery.
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