Meta-analysis: Vena Cava Filters Safe, Effective in Reducing Pulmonary Embolism

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Placement of a prophylactic inferior vena cava (IVC) filter pares the rate of overall and fatal pulmonary embolism without exposing trauma patients to a higher risk of deep vein thrombosis (DVT) or mortality, according to a meta-analysis published in the February 2014 issue of JAMA: Surgery.

IVC filters may be used to reduce the rate of pulmonary embolism when trauma places patients on anticoagulants at high risk of excess bleeding.

For the meta-analysis, investigators led by Elliott R. Haut, MD, of Johns Hopkins University Medical Center (Baltimore, MD), analyzed data from 6 single-center studies evaluating 1,064 patients who received standard VTE therapy with (n = 334) or without (n = 730) an IVC filter:

• 1 small pilot feasibility randomized controlled trial
• 1 prospective cohort study with concurrent comparison groups
• 3 prospective cohort studies with historical controls
• 1 retrospective cohort study

IVC filter placement consistently reduced occurrences of pulmonary embolism, both overall and fatal. Using a baseline pulmonary embolism risk of 1.15% among trauma patients, the number needed to treat (NNT) to prevent 1 additional pulmonary embolism with IVC filters was estimated to be 109, while the NNT to prevent 1 fatal pulmonary embolism was 1,099. No differences in incidence of DVT or mortality were found between groups (table 1).

Table 1. Adverse Event Risk: IVC Filter vs No Filter

^a P = 0.38

Though the authors note consistent results, they rank the strength of available evidence as “low” in supporting a reduction of overall and fatal pulmonary embolism and “insufficient” to support a reduction in mortality or change in the probability of DVT.

Debate Rages On

IVC filter use varies greatly among trauma centers, perhaps due to conflicting surgical guidelines, Dr. Haut and colleagues say. Overall use of the filters is on the rise, they explain, though some maintain that the preventative measure causes more harm than benefit, as the filters have been associated with increased risk of thrombotic and mechanical complications. Others argue the filters may prevent life-threatening cases of pulmonary embolism with limited risk to patients. In this regard, the authors hope the results of the meta-analysis will be used to update and universalize surgical guidelines.

“Clinicians need guidance regarding the use of prophylactic IVC filters in high-risk trauma patients,” the investigators advise. Alongside reductions in pulmonary embolism, “risks to patients with IVC filter placement remain, and we were unable to fully examine these risks in this review,” they write.

In most patients receiving VTE prophylaxis, the risks of filter placement likely outweigh the benefits but that tradeoff probably differs for patients who are more likely to develop pulmonary embolism, the authors explain. “As with many patient care decisions, these difficult clinical judgments must balance the ratio of benefit to harm for individual trauma patients,” they conclude.

Study Details

Mean patient age ranged from 31.4 to 58.4 years, and most were men (58-96%). The most common form of standard therapy was a combination of venous compression devices with subcutaneous low-molecular-weight heparin. Where data were available, mean Injury Severity Scores were higher in the IVC filter group compared with the no-filter group, indicating higher severity of trauma.

Source:
Haut ER, Garcia LJ, Shihab HM, et al. The effectiveness of prophylactic inferior vena cava filters in trauma patients: a systematic review and meta-analysis. JAMA Surg. 2014;149:194-202.

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