Once again, after decades of common use, a frequently implanted device has been found to confer no benefit whatsoever over a much less invasive therapy. Cardiologists and radiologists often implant the device, called a retrievable inferior vena cava filter, inside people who are at high risk for developing potentially lethal blood clots. The filter is designed to prevent pulmonary embolism, an extremely dangerous condition that occurs when a blood clot from the legs migrates into the lungs. Now a new study published in JAMA shows that these devices provide no advantage over anticoagulant drugs which thin the blood.
A group of French physicians randomized nearly 400 hospitalized patients with acute, symptomatic pulmonary embolism (PE) to receive a retrievable inferior vena cava (IVC) filter in addition to anticoagulation or anticoagulation alone. At 3 months, recurrent PE had occurred in 6 patients (3%) in the filter group compared with 3 patients (1.5%) in the control group. The two-fold increase in risk with the filter was not statistically significant. All 6 cases in the filter group and 2 of the 3 cases in the control group were fatal. Between three and six months there was one additional case of recurrent PE in each group.
The authors note that the increased use of filters has likely been fueled by the availability of retrievable inferior vena cava filters. Their results show that these devices confer “no benefit in terms of pulmonary embolism recurrence or mortality” in these patients.
Based on previous studies the authors say they had anticipated a much higher rate of recurrent PE, about 8%, in the control group. “We believe that the low rate of events observed in the control group of our study is consistent with contemporary care, indicating that modern management with full-dose anticoagulation therapy is likely very effective even in patients usually considered to be at high risk for recurrence, rendering unnecessary additional therapy such as inferior vena cava filters,” they write. In addition, ”we believe that our negative findings likely reflect the low event rate with effective anticoagulation alone rather than lack of filter efficacy.” They note, however, that they excluded patients who were unable to take an anticoagulant or who had a recurrence despite adequate anticoagulation.
In 2013 a study published in JAMA Internal Medicine found an extremely wide range of use of IVC filters in US hospitals. An accompanying viewpoint raised the question: “how could a medical device be so well accepted without any evidence of efficacy?”
All the filters in the trial were supplied by a French manufacturer, ALN Implants Chirurgicaux. Other companies that manufacture IVC filters include Argon Medical Devices, B Braun Interventional Systems, Bard Peripheral Vascular, Cook Incorporated, Cordis Corporation, and Volcano Corporation.
In addition to warfarin, which is available as an inexpensive generic, four new oral anticoagulant drugs have been approved for the treatment and prevention of VTE and PE. These drugs are dabigatran (Pradaxa, Boehringer Ingelheim), rivaroxaban (Xarelto), apixaban (Eliquis, Bristol-Myers Squibb and Pfizer), and edoxaban, (Savaysa, Daiichi Sankyo).
Source: Forbes Health