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Weighing the Available Evidence: IVC Filters
LETTER
Weighing the Available Evidence: IVC Filters To the Editor: In his review article about inferior vena cava filters,1 Crowther rightly condemned the non– evidence-based use of these devices. Several issues about the existing evidence deserve a mention to present a balanced picture. First, in their landmark study, Decousus et al,2 for obvious reasons, did not perform a head-to-head analysis of filters versus anti-coagulation. Both the filter and no-filter group were treated with heparin and at least 3 months of Coumadin (warfarin), which is not the usual clinical scenario; we as physicians very rarely recommend that patients get both Coumadin (warfarin) and a filter. A protocol in which one arm was not anticoagulated and received just filters would have resulted in an ethical dilemma of deviating from the standard of care and protocol approval difficulties. Second, the very population that the author has mentioned as the only legitimate group to receive filters according to American College of Chest Physicians guidelines3 (patients with contra-indications to or complications from anti-coagulation) were excluded by Decousus et al. So this population never has been studied in a large randomized trial. Third, in the words of Greenfield, “Given the choice, I suspect . . . most patients would prefer deep venous thrombosis to pulmonary embolism.”4 A filter is not designed to prevent deep venous thrombosis, but rather the more lethal sequel, the pulmonary embolism, and it does that as shown by the long-term (8-year) follow-up of the same population by Decousus in the PREPIC (Prevention du Risqué d’Embolie Pulmonaire par Interruption Cave) study.5 If
0002-9343/$ -see front matter © 2008 Elsevier Inc. All rights reserved.
filters are responsible for deep venous thrombi while doing what they are supposed to do, we have to remember that anti-coagulation is not free of complications either. The above is not an attempt to suggest that filters are somehow superior to the present standard of care (anticoagulation). In the complicated world of venous thromboembolism, however, they cannot be denied a place. It all boils down to the good old risk-benefit ratio for each individual patient. M. Ayaz Mir, MBBS Division of Hematology University at Buffalo Buffalo, NY
doi:10.1016/j.amjmed.2007.10.037
References 1. Crowther MA. Inferior vena cava filters in the management of venous thromboebmolism. Am J Med. 2007;120(10 Suppl 2):S13-S17. 2. Decousus H, Leizorovicz A, Parent F, et al. A clinical trial of vena caval filters in the prevention of pulmonary embolism in patients with proximal deep venous thrombosis. Prévention du Risque d’Embolie Pulmonaire par Interruption Cave Study Group. N Engl J Med. 1998;338(7): 409-415. 3. Buller HR, Angelli G, Hull RD, et al. Antithrombotic therapy for venous thromboembolic disease: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest. 2004;126(Suppl 3): 401S-428S. 4. Greenfield LJ. The PREPIC Study Group. Eight-year follow-up of patients with permanent vena cava filters in the prevention of pulmonary embolism: the PREPIC (Prevention du Risque d’Embolie Pulmonaire par Interruption Cave) Randomized Study. Perspect Vasc Surg Endovasc Ther. 2006;18(2):187-188. 5. PREPIC Study Group. Eight-year follow-up of patients with permanent vena cava filters in the prevention of pulmonary embolism: the PREPIC randomized study. Circulation. 2005;112:416-422.
Weighing the Available Evidence: IVC Filters To the Editor: In his review article about inferior vena cava filters,1 Crowther rightly condemned the non– evidence-based use of these devices. Several issues about the existing evidence deserve a mention to present a balanced picture. First, in their landmark study, Decousus et al,2 for obvious reasons, did not perform a head-to-head analysis of filters versus anti-coagulation. Both the filter and no-filter group were treated with heparin and at least 3 months of Coumadin (warfarin), which is not the usual clinical scenario; we as physicians very rarely recommend that patients get both Coumadin (warfarin) and a filter. A protocol in which one arm was not anticoagulated and received just filters would have resulted in an ethical dilemma of deviating from the standard of care and protocol approval difficulties. Second, the very population that the author has mentioned as the only legitimate group to receive filters according to American College of Chest Physicians guidelines3 (patients with contra-indications to or complications from anti-coagulation) were excluded by Decousus et al. So this population never has been studied in a large randomized trial. Third, in the words of Greenfield, “Given the choice, I suspect . . . most patients would prefer deep venous thrombosis to pulmonary embolism.”4 A filter is not designed to prevent deep venous thrombosis, but rather the more lethal sequel, the pulmonary embolism, and it does that as shown by the long-term (8-year) follow-up of the same population by Decousus in the PREPIC (Prevention du Risqué d’Embolie Pulmonaire par Interruption Cave) study.5 If
0002-9343/$ -see front matter © 2008 Elsevier Inc. All rights reserved.
filters are responsible for deep venous thrombi while doing what they are supposed to do, we have to remember that anti-coagulation is not free of complications either. The above is not an attempt to suggest that filters are somehow superior to the present standard of care (anticoagulation). In the complicated world of venous thromboembolism, however, they cannot be denied a place. It all boils down to the good old risk-benefit ratio for each individual patient. M. Ayaz Mir, MBBS Division of Hematology University at Buffalo Buffalo, NY
doi:10.1016/j.amjmed.2007.10.037
References 1. Crowther MA. Inferior vena cava filters in the management of venous thromboebmolism. Am J Med. 2007;120(10 Suppl 2):S13-S17. 2. Decousus H, Leizorovicz A, Parent F, et al. A clinical trial of vena caval filters in the prevention of pulmonary embolism in patients with proximal deep venous thrombosis. Prévention du Risque d’Embolie Pulmonaire par Interruption Cave Study Group. N Engl J Med. 1998;338(7): 409-415. 3. Buller HR, Angelli G, Hull RD, et al. Antithrombotic therapy for venous thromboembolic disease: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest. 2004;126(Suppl 3): 401S-428S. 4. Greenfield LJ. The PREPIC Study Group. Eight-year follow-up of patients with permanent vena cava filters in the prevention of pulmonary embolism: the PREPIC (Prevention du Risque d’Embolie Pulmonaire par Interruption Cave) Randomized Study. Perspect Vasc Surg Endovasc Ther. 2006;18(2):187-188. 5. PREPIC Study Group. Eight-year follow-up of patients with permanent vena cava filters in the prevention of pulmonary embolism: the PREPIC randomized study. Circulation. 2005;112:416-422.