IVC Filters Overused, Unproven

(April 26, 2018)  PulmCC, a trade publication for pulmonary and critical care, published an article on Dec. 16, 2016 titled, “Inferior vena cava filters are overused.  What’s the harm?”  The piece details the puzzling acceptance of IVC filters despite a decided lack of evidence proving their efficacy.  It asks several pertinent questions about whether inferior vena cava filters are being used in safe or necessary ways.

The PulmCC piece also asks why patients with IVC filters aren’t receiving notices to have them removed.  Evidence shows that the longer a temporary IVCF remains in a person’s vena cava, the more likely it is to cause problems.  Shouldn’t IVCF makers and the parties that implant them be under some obligation to patients to keep them informed until the filters are safely removed?

Some people, such as trauma victims, might receive an IVC filter and never even know they have one, until, perhaps, it is too late to have it safely removed.

Inferior vena cava filters are placed in the vena cava, the vein returning blood to the heart from the legs, to prevent deep venous thromboses (DVT) – blood clots in the legs – from traveling to the heart and lungs, causing pulmonary embolism (PE).  PulmCC notes that, “[D]espite their wide use, the benefits and risks of IVCF remain unclear. With about 50,000 IVC filters placed annually in the U.S., that’s a lot of unclarity.”

A Lack of Clarity
“Unclarity” is a charitable way to put it.  The publication also notes that IVCF are often used in conjunction with anti-coagulation therapy, and it asks whether this is good medicine. It’s a fair question, especially as studies have shown that adding an IVCF to go with anticoagulation therapy gives no mortality benefit to the patient.

IVC filters are the standard of care for people with acute pulmonary embolism or proximal DVT who cannot receive anticoagulation because of bleeding risk. But IVCF are used more often as an additional preventive therapy along with anticoagulation in an attempt to further reduce PE risk.

Scant Evidence for IVC Filter Benefits
Evidence supporting IVCF for any indication is scant, at best. Two large randomized trials have failed to show any mortality benefit from IVC filters.

Two IVC Filter Studies show no IVCF Benefits
PREPIC (1998) study participants with either DVT or PE who received IVCF, had fewer recurrent PEs, but suffered more DVTs, and had no mortality reduction. PREPIC studied non-retrievable filters. Half its patients had routine DVTs without PE. PREPIC confirmed that routine placement of permanent IVC filters in DVT and PE is not a good idea. After PREPIC, nearly all IVCF placed in the U.S. today are retrievable.

PREPIC2’s (2015) updated design tested retrievable IVCF (with anticoagulation, vs anticoagulation alone) enrolling ~400 ‘high risk’ patients with acute PE. There was no difference in death or recurrent PE between groups at 3 or 6 months. Although closer to real-world practice today, ‘high risk’ in PREPIC2 included anyone over 75, or with any active cancer diagnosis, which are not widely accepted indications for IVCF. Fewer than 18% of patients in PREPIC2 had any hypotension during their hospitalization.

Some Benefit for Elderly
A retrospective review of a large inpatient database, however, did show IVC to be associated with improved survival in elderly patients with massive PE (i.e., with hypotension). But no randomized trial testing this IVCF indication has been performed, probably because this is a small subset of patients.

Professional Society Disagreements on IVC Filters
Only two indications for IVCF are generally accepted by all major professional societies:

1.  Acute PE or proximal DVT with inability to provide anticoagulation;
2.  Patients with hemodynamically unstable PE, for whom another PE might be fatal.

Professional societies mostly disagree on appropriate indications for IVC filters. For example, the American College of Radiology (ACR) supports prophylactic placement of IVCF in patients with severe trauma or spinal injury without DVT, but the American College of Chest Physicians (ACCP) advises against it. Similarly, ACCP endorses IVCF placement as an adjunctive measure for massive PE treated with thrombolysis*, but American Heart Association (AHA) disagrees.

Radiology professional societies, whose members commonly place IVC filters – for a price, of course – endorse more IVCF indications than do ACCP and AHA. (Medicare pays roughly $3,800 to install an IVCF, another $2,250 to remove it.)

*ACCP advises against the routine use of IVCF in PE and DVT but adds “our recommendation against insertion of an IVC filter in patients with acute PE who are anticoagulated may not apply to [patients with hypotension].”

Temporary IVC Filters not removed
Most “retrievable” IVC filters become permanent. Less than a third of them are ever removed. “Patient lost to follow-up” is the oft-cited reason, but PulmCC says, “[F]ailure to remove an IVCF is more likely due to inadequate communication and care coordination by physicians between the inpatient and outpatient settings.”

IVC Filter Risks Unknown
IVC filter risks are largely unknown, because no IVCF maker or medical entity has set up a comprehensive public repository for adverse events from IVCF. Complications of IVCF placement frequently occur, according to PulmCC; but the rate of real harm is unknown. IVC filters have been generally considered reasonably safe mainly because hundreds of thousands have been placed without large safety signals emerging, says PulmCC; but that may be changing.

IVC Filters Overused, Unproven

A retrospective review of 952 patients after IVCF placement suggested a 1% rate of serious complications from IVCF. After receiving thousands of adverse event reports, the FDA advised physicians to remove IVC filters as soon as feasible – ideally within two months – and demanded additional longitudinal product safety data from IVCF makers. The PRESERVE trial is ongoing in response. IVC filter lawsuits asserting negligence and product defects are pending against at least three IVC filter manufacturer: Cook Medical, C.R. Bard, and Rex Cordis.

IVC Filters are Big Business
IVC filters are a roughly $200 million business. Hospitals split the profits with the interventional physician (radiologist, surgeon, cardiologist).

PulmCC asks, “With all that money sloshing around, and the payment on the table for IVC filter removal, why can’t doctors, hospitals and industry at least get organized enough to take them out?”

The publication suggests that a hospital could schedule a removal for a time after the patient leaves the hospital. IVCF makers could maintain a registry, pay call center reps or robots to reach IVCF recipients by phone, mail, and email until the filter is removed They could add follow-up money to the device cost, and have FedEx deliver a package to the patient’s home as a reminder to remove the filter.

PulmCC closes by saying that, “Blaming the patient and primary physician for IVC filters left in place won’t cut it anymore.”

The publication takes doctors to task for not promptly removing the filters, but don’t the IVCF manufacturers have a greater responsibility? How clear have they made it to doctors that the longer a filter stays in place, the more likely it is to cause problems?

An upcoming IVC filter trial in Houston, Texas, beginning May 15, 2018, will attempt to answer this question and many more regarding the safety and efficacy of IVC filters. The trial specifically concerns the Cook Celect IVC filter made by Cook Medical of Indianapolis, Indiana.

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