A recent series of 4 articles has questioned the efficacy of inferior vena cava filters for the treatment of pulmonary embolism.
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An article by White et al
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documents the tremendous variation in the use of vena cava filters. They determined the use of filters in nontrauma patients with acute venous thromboembolism in 263 hospitals. The overall incidence was 14.95%. However, the use varied from 0% to 38.96%! This incredible variation was not explained by different patient characteristics. They suspected that the variation was related to “the enthusiasm of specific physician leaders within each hospital who advocate for or against the use of filters.”1
This wide variation in the use of vena cava filters reflects the uncertainty about the indications for their use.There is near-universal agreement that filters are indicated in patients with acute venous thromboembolism in whom anticoagulation is contraindicated. An additional indication that some advocate is hemodynamically unstable pulmonary embolism.
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It is believed that a decrease in the early recurrence rate of pulmonary embolism in this clinical situation could decrease mortality.The only randomized controlled trial of filters in venous thromboembolism
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was of 400 patients with proximal deep vein thrombosis. There was a significant decrease in recurrent pulmonary embolism in the first 12 days in patients with a filter compared with anticoagulation alone (1.1% vs 4.8%, P = .03). However, there was no decrease in early mortality. Because less than half of these patients had pulmonary embolism before randomization and none had unstable pulmonary embolism, one would not expect a significant decrease in early mortality.The article by Sarosiek et al
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reports the experience with vena cava filters in 952 patients. Only 504 patients had venous thromboembolism. They reported a 7.8% incidence of venous thromboembolism after filter placement. There were no controls, so the incidence of venous thromboembolism in comparable patients without filters was not determined. They concluded that the use of filters results in suboptimal outcomes due to high rates of venous thromboembolism.2
An accompanying Viewpoint by Prasad et al
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concluded: “given the known harms and the lack of efficacy data for vena cava filters, we need randomized clinical trials.” An editor's note by Katz4
referred to the “lack of data on the effectiveness of the filter, and the growing evidence of harm.”There is, in fact, impressive evidence of the effectiveness of vena cava filters in patients with hemodynamically unstable pulmonary embolism defined as in shock or requiring ventilator support. Stein et al
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reported the outcome of therapy in over 70,000 patients with unstable pulmonary embolism who were treated in 1000 US acute care hospitals from 1999 through 2008.This was not a randomized controlled trial. The therapeutic decisions were made by thousands of US physicians in an era in which the indications for vena cava filters other than a contraindication to anticoagulation were controversial.
The outcomes of therapy in these patients with unstable pulmonary embolism are shown in the Table.
TableMortality in Patients with Unstable PE
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| Therapy | No. Treated | Hospital Mortality |
|---|---|---|
| Anticoagulants alone | 38,000 | 51% |
| Anticoagulants with VCF | 23,850 | 33% |
| Embolectomy alone | 430 | 58% |
| Embolectomy with VCF | 520 | 25% |
| Thrombolytic RX alone | 14,760 | 18% |
| Thrombolytic RX with VCF | 6630 | 7.6% |
PE = pulmonary embolism; RX = treatment; VCF = vena cava filter.
The hospital mortality in unstable patients with standard anticoagulant therapy alone was 51%. When filters were added to the therapy, the mortality was 33% (P <.0001).
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The mortality in unstable patients with embolectomy alone was 58%. When filters were added, mortality was 25% (P <.0001).
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In unstable patients receiving thrombolytic therapy alone, the mortality was 18%. When filters were added, the mortality was 7.6% (P <.0001).
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These reductions in the mortality of unstable pulmonary embolism when filters are added to anticoagulant therapy, thrombolytic therapy, or pulmonary embolectomy are highly significant.
There has been only one randomized clinical trial of vena cava filters for the treatment of venous thromboembolism
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in the more than 45 years since transvenous filters were introduced to clinical practice. There are no randomized clinical trials of filters for the treatment of patients with hemodynamically unstable pulmonary embolism. Is it likely that such a trial is on the horizon?We believe that there is sufficient evidence to recommend the use of vena cava filters in patients with hemodynamically unstable pulmonary embolism.
References
- High variation between hospitals in vena cava filter use for venous thromboembolism.JAMA Intern Med. 2013; 173: 506-512
- Indications, complications, and management of inferior cava filters.JAMA Intern Med. 2013; 173: 513-517
- The inferior vena cava filter. How could a medical device be so well accepted without evidence of efficacy?.JAMA Intern Med. 2013; 173: 493-495
- Inferior cava filters. The harms are clear, the benefits less so.JAMA Intern Med. 2013; 173: 495
- Thrombolytics and vena cava filters decrease mortality in patients with unstable pulmonary embolism.Am J Med. 2012; 125: 429-430
- A clinical trial of vena cava filters in the prevention of pulmonary embolism in patients with proximal deep- vein thrombosis.N Engl J Med. 1998; 338: 409-415
- Impact of inferior vena cava filters on in-hospital case fatality rates from pulmonary embolism.Am J Med. 2012; 125: 478-484
- Case fatality rate with pulmonary embolectomy for acute pulmonary embolism.Am J Med. 2012; 125: 471-477
Article info
Footnotes
Funding: None.
Conflict of Interest: Neither author has a conflict of interest.
Authorship: Both authors had access to the data and a role in writing the manuscript.
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© 2013 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
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- Observational Studies Cannot Justify the Inferior Vena Cava FilterThe American Journal of MedicineVol. 127Issue 3
- PreviewIn their commentary, Dalen and Stein1 criticize my conclusions. With my colleagues, after extensive review, we concluded that there was no good evidence for the inferior vena cava filter’s efficacy regarding any patient-centered end point,2 and only clear evidence of harm. We called for proponents to show that this device can benefit any group of patients in a randomized controlled trial as a condition for continued use.
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