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Value of vena cava filter after bariatric surgery questioned

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – The practice of inserting a filter in the inferior ven cava before performing gastric bypass surgery does not reduce the postoperative occurrence of pulmonary embolisms and only increases complications, according to a report in the August issue of the Annals of Surgery.

In the introduction to their paper, Dr. Nancy J. O. Birkmeyer at the University of Michigan, Ann Arbor, and colleagues in the Michigan Bariatric Surgery Collaborative note that the use of inferior vena cava (IVC) filters to capture thromboemboli from the lower extremities is controversial but increasingly used. “Because IVC filters are associated with substantial risks and costs, evidence of their effectiveness is important.”

To investigate, the group identified 6376 patients undergoing gastric bypass Surgery, of whom 542 (8.5%) underwent preoperative IVC filter placement.

After propensity adjustment, the IVC filter patients were no less likely to have postop venous thromboembolism than the non-filter patients (0.66% vs. 0.51%); the odds ratio of 1.28 was not statistically significant.

Similarly, risks were not significantly different for serious complications (4.82% vs. 3.67%) and for death or permanent disability (1.13% vs. 0.52%). In fact, the authors report, “More than half (57%) of the IVC filter patients in the latter group had a fatal pulmonary embolism or complications directly related to the IVC filter itself, including filter migration or thrombosis of the vena cava.”

They do caution that the study, although large, included a relatively small number of adverse events, so statistical power to demonstrate significant harm from IVC filter use was limited. Here was also a potential for selection bias,

Nonetheless, Dr. Birkmeyer and colleagues conclude, “We believe that the use of IVC filters for VTE prophylaxis in bariatric surgery should be limited pending evidence of benefit for high-risk patients in randomized clinical trials.”

Reference:

Preoperative Placement of Inferior Vena Cava Filters and Outcomes After Gastric Bypass Surgery

Ann Surg 2010;252: 313–318.