March 26th, 2013
Should the Use of IVC Filters be Filtered Until We Have More Data?
Preventing pulmonary embolism (PE) by interrupting the inferior vena cava (IVC), first introduced by Trousseau during the mid-1800s, has received growing attention lately with recent studies showing a remarkable increase in their use (e.g., Stein et al and Duszak et al). But what is the evidence base behind this mechanistically appealing approach? The largest randomized trial for the use of IVC filters was the PREPIC (Prevention du Risque d’Embolie Pulmonaire par Interruption Cave) trial. PREPIC enrolled 400 (of the anticipated 800) patients with proximal deep vein thrombosis (with or without PE), 94% of whom received anticoagulation for at least three months. Placement of IVC filters was associated with reduced risk of PE, but increased risk of deep vein thrombosis, with no mortality difference at 2-year or 8-year follow-up.
The available expert statements and guidelines, including those by the AHA and the ACCP, however, recommend IVC filters mostly for cases with contraindications to anticoagulation or those with recurrent PE despite receiving anticoagulation; two reasonable recommendations for which we lack data from high-quality, comparative effectiveness studies.
Lack of convincing evidence, costs and expertise considerations, as well as local culture effects may lead into variations for use of IVC filters in the spectrum of patients with venous thromboembolism (VTE). Using the administrative data from 263 hospitals in California, White and colleagues recently showed a remarkable variation in use of IVC filters for acute VTE hospitalization across hospitals, from 0% to 38.96% (interquartile range: 6.23%-18.14%). Even among geographically close hospitals, such variations were remarkable. Of note, the hospital effect persisted even after extensive adjustment for clinical factors and comorbidities.
Despite the potential benefits, placing filters is costly and is not risk-free, making it a challenging decision for patients, physicians, and society, and the lack of high-quality evidence hampers the selection of the best possible decisions. There is a real need for definitive trials to answer the questions about the utility of IVC filters for the existing indications, as stated recently. I have heard that a group of investigators are about to launch a large, multicentric randomized trial in that regard. Until then, perhaps anticoagulation should remain the cornerstone of VTE treatment. While use of IVC filters is most plausible in patients with contraindications for anticoagulation, we simply lack high-quality comparative effectiveness data to support this appealing option.
What are your reflections on this issue? Where do you see the future of IVC filters?