Cook Medical IVC Filters: Likely Harmful, Possibly Useless

Cook Medical, a company based in Indiana, manufactures two of the nation’s leading retrievable IVC filters, net-shaped devices designed to capture blood clots before they reach a patient’s lungs. First approved in 2000, Cook’s Günther Tulip filter quickly became a popular choice for surgeons treating patients at an increased risk of pulmonary embolism. The company’s Celect model would follow in 2007, offering physicians even more treatment options.

medical ivc filters

But soon after their release, reports of serious injuries – even deaths – began to fill the Food & Drug Administration‘s adverse event reporting system. Hundreds of physicians voiced their concerns, and now it seems clear that IVC filters are prone to break, sending dangerous shards of metal hurtling through the circulatory system.

Beyond Severe Risks, Cook’s Filters May Be Useless

Even worse, recent analyses have found little evidence to support the very use of IVC filters in the first place. A review conducted by the Journal of the American Medical Association (JAMA) turned up only one study on the subject – a paper that found, while IVC filters may decrease the risk of pulmonary embolism, that benefit is negated by their ability to increase the risk of deep vein thrombosis.

In fact, physicians across the world are only now beginning to call for major studies on the safety and efficacy of IVC filters. In various forms, the devices have been in use since the 1960s, but we still know little – close to nothing – about what effect they can have on a patient’s chances of survival. At the same time, mounting evidence has shown the medical community that IVC filters pose serious health risks. As Dr. Mitchell Katz, an editor at JAMA, put it: “the harms are clear, the benefits less so.” In his own clinical practice, Katz says he will no longer ” ‘recommend’ an inferior vena cava filter.” Instead, he “intend[s] to discuss with […] patient[s] the lack of data on the effectiveness of the filter and the growing evidence of the harm.”


Patients, many of whom have suffered serious injuries, have reacted with shock and outrage. But their initial anger has turned to concerted action, and now more than 200 people have filed personal injury lawsuits against Cook.

Broken IVC Filter Pierces Patient’s Vital Organs

Lara Adams received a Cook IVC filter, the Celect model, in 2009. At first, everything seemed fine. Adams’ chest x-rays returned normal, and she returned home three days after the implantation procedure. A follow-up several months later revealed that the filter had tilted out of position a bit, but her doctors were confident that it would remain effective.

It was only on March 11, 2011, nearly two years after Adams had received her implant, that she knew something was wrong. “Crippled” by inexplicable pain, Adams rushed to the hospital, where doctors first attributed her discomfort to a kidney stone. But a CT scan revealed evidence that her IVC filter had “broke[n] apart.” Several of the device’s fragments had “migrated throughout her body,” lodging in her lungs and liver. One of the filter’s fractured struts was left “embedded” in her inferior vena cava, the large vein in which IVC filters are implanted.

Three days later, Adams went into surgery. Doctors were successful in removing what remained of her IVC filter, but have been unable to retrieve the fragments piercing her internal organs. Based on her own personal experience, Adams can say without doubt that Cook’s filter was far from the “safe and effective treatment” option she was led to believe.

Along with her husband, Lara Adams filed a product liability lawsuit (PDF) against Cook Medical on January 4, 2013. In her complaint, filed in the US District Court for the Southern District of Indiana, Adams accuses Cook of withholding critical safety information from physicians and patients, including evidence that the company’s IVC filters are prone to breakage and migration.

Her allegations are shared by hundreds of other injured patients, and legal experts believe that thousands more may be entitled to pursue compensation.

How Indiana MDL Affects Cook IVC Filter Lawsuits

Today, the IVC filter lawsuits filed against Cook have been “consolidated” in the US District Court of Indiana. This legal mechanism, known as Multi-District Litigation (MDL), is frequently employed to gather similar lawsuits together, in the same federal court under a single judge.

In Indiana, the lawsuits will continue through pre-trial proceedings together, led by a select group of plaintiffs’ attorneys appointed by the court. This Plaintiffs’ Steering Committee guides the evidence-gathering process and develops legal arguments. When the lawsuits have been prepared for trial, it’s likely that several “bellwether” cases will be selected and heard before a jury first. These initial trials are often a crucial step, allowing plaintiffs and defendants to gauge the responses of future juries.

Bellwether trials often lead to increasingly serious settlement negotiations, but this isn’t a class action. Each lawsuit remains an individual legal action, under the control of its plaintiff or plaintiffs. If settlement offers are unacceptable, plaintiffs are free to push for a trial, which usually takes place in the original court where their lawsuit was filed.

Unusually High Perforation Rates

In 2013, two teams of researchers, one from the University of Colorado and the other at Northwestern, set out to test how retrievable “retrievable” IVC filters actually are. They pit Cook’s Celect filter against one of its competitors, the Option filter manufactured by Pennsylvania’s Rex Medical.

At first, the study’s goal was fairly simple: figure out how easily each filter can be removed from patients. Ultimately, the teams attempted retrieval in 58 patients implanted with Cook’s IVC filter and 65 patients with the Option. On balance, Cook filters were easier to remove; the retrieval procedure failed for only 3.4% of patients, while the surgeons were unable to remove 7.7% of the Option filters. Cook’s devices also tilted less than the ones manufactured by Rex Medical. Almost 17% of Rex’s filters had leaned away from their proper position, while only around 9 of the Celect devices had.

But the study’s most astounding result, and the one upon which researchers would fixate, was the rate of perforation. In 65 patients, not one Option filter had pierced the vena cava. Cook Medical’s Celect filter, on the other hand, had perforated the vein in 43% of patients.

Perforation “Rule Rather Than Exception”

In San Francisco, a group from the University of California found that Cook Medical filters perforate the vena cava more often than not. In all but 7 of the 50 patients under review, the struts of Cook’s filter had pierced the vein, and a large proportion, 40%, were found to have tilted.

The longer a filter stayed in, the more likely it was to perforate, a complication making retrieval difficult. The surgeons were unwilling to attempt removal in most cases, finally extracting only 11 of the IVC filters. Every IVC filter that was implanted for 71 days or longer caused some degree of perforation.

Retrieving IVC filters has proved difficult for many surgeons. The fact that retrievable filters, a relatively recent innovation, were approved without specific recommendations for their removal didn’t help much. This is no small risk. Complications seem to increase when filters are left in for longer periods of time, the FDA reported in May of 2014, noting its worry that doctors have failed to remove the devices, even after a patient’s risk of pulmonary embolism subsides.

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