In a presentation at the International Symposium on Endovascular Therapy (ISET), 19–23 January 2013, Miami, Florida, USA, Matthew Johnson (Indiana University, Indiana, USA) spoke to delegates about the trends in using inferior vena cava filters in the USA and reported on progress surrounding an upcoming multicentre study to examine their use.
Johnson said that inferior vena cava filters “have been used in the treatment of patients with venous thromoembolism for decades.” He added that the trend, since the early 2000s, was to use retrievable inferior vena cava filters that have cleared by the Food and Drug Administration (FDA) 510(k) approval process. He added that, in 2010, over 200,000 retrievable inferior vena cava filters were placed. Johnson said that currently “Many, perhaps the majority, of retrievable inferior vena cava filters are being placed in people as prophylactic measures against venous thromboembolism.”
Since November 2010, when the FDA created a series of defined questions in order to assess the safety and efficacy of retrievable inferior vena cava filters, discussions have been ongoing between them, the Society of Interventional Radiology and the Society for Vascular Surgery.
According to Johnson, the FDA issued a safety communication on 9 August 2010, suggesting that retrievable inferior vena cava filters should be removed when they are no longer required. The communication was issued after a perceived increase in filter-related complications, according to the MAUDE (Manufacturer and user facility device experience) database. The complications outlined by MAUDE were: caval perforation, filter fracture, migration and embolization.
In Johnson’s opinion, randomised controlled trials were inadequate to address the “complicated landscape” of using filters and that registries (such as MAUDE) have “no denominator.” He suggested that a prospective study with definitions such as study population, devices, goals, terms, methodology and outcomes would be favourable to randomised controlled trials.
The Society of Interventional Radiology and the Society of Vascular Surgery are now in the process of determining a framework for the PRESERVE (Predicting the safety and effectiveness of inferior vena cava filters) study, Johnson noted, with the goal of obtaining a functional view of all filters placed in the United States. PRESERVE, which was originally presented to the FDA on 10 August 2012, will aim to evaluate the safety and effectiveness of inferior vena cava filters and answer the FDA’s defined questions.
The PRESERVE study is a prospective, multicentre, single-arm clinical trial of adults in whom inferior vena cava filters are clinically indicated. The primary endpoints are safety (freedom from major complications) and effectiveness (freedom from pulmonary embolism). Johnson told delegates that it is expected that about 2,500 subjects will be enrolled in the study with a predicted 300 subjects per filter type. The patients whose filters are removed will be followed up three months after removal.
“The PRESERVE trial represents a paradigmatic shift, in which each group has agreed to work together to address an important healthcare concern,” said Johnson. “The PRESERVE trial also represents a shift toward recognition that demonstration of safety and efficacy may not necessarily require a randomised controlled trial.”
Johnson added that the IVC Filter Study Group Foundation, a joint foundation founded by the Society of Interventional Radiology and the Society of Vascular Surgery will choose the contract research organisation (CRO) to run the study.