Boston Medical Center researcher Dr Shayna Sarosiek has been discussing (with heartwire) the results of a study into Inferior Vena Cava (IVC) filters in this large and busy trauma center. In her work, presented at the American Society of Haematology 2011, Dr Sarosiek and co-investigator, Dr J Mark Sloan, found that less than 10% of retrievable IVC filters were removed from patients, despite the fact that the indication for the filter placement was no longer present at discharge. The research also indicated that one in five patients could not have the filter removed, making this a “common and underrecognized problem.”
Sarosiek, after presenting the results of the study told heartwire that there are few treatment options for patients at risk of venous thromboembolism (VTE) who are contraindicated for anticoagulation therapy, a condition associated with significant morbidity and mortality, but temporary IVC filters can be placed in these patients for the prevention of pulmonary embolism.
Sarosiek undertook this research project because she saw numerous patients who still had an IVC in place and was unsure whether or not to continue with anticoagulation in these patients. In this analysis, 25% of patients who received a filter were receiving anticoagulation therapy at the time of discharge, and slightly less than 50% of the 504 patients with VTE at the time of filter placement were also receiving therapeutic anticoagulation. “At present, there are not a lot of data supporting patients continuing with or starting anticoagulation therapy when they have an IVC filter”, said Sarosiek.
Using retrospective data between 2003 and 2011 from the Boston Medical Center, Sarosiek and Sloan analysed the indications for filter use, as well as filter complications, retrieval rates, and follow-up of 952 patients who received IVC filters at the center.
Approximately half of the filters were implanted after trauma, blunt trauma, motor-vehicle collisions, penetrating trauma, and falls.
Of the patients who received a filter, 273 received a permanent device and 679 received a retrievable IVC filter. The first retrievable filter was implanted in 2006, and from that point on the majority of patients received the retrievable device.
To heartwire, Sarosiek said that the IVC filters were placed by five medical and surgical services: radiology (n=626), surgery (n=249), vascular surgery (n=37), cardiology (n=21), and cardiothoracic surgery (n=1). The devices were typically implanted after a median of three days following the trauma, although 106 filters were implanted more than one week after the trauma.
“The retrievable filters can be left in permanently, although I would say that the majority of these patients only had a temporary reason why they couldn’t be anticoagulated, and yet the filter remained in place after they were sent home,” said Sarosiek. “Roughly 25% of all of these patients were fully anticoagulated before they left the hospital, which means the filter should have come out.”
Why were removable filters left in place?
Overall, retrieval was not attempted in 608 patients (89%). Asked why the filters are not removed, Sarosiek said a lack of follow-up is the main reason. “The filters are placed by five different services within the hospital, but there’s not one assigned group of providers that follow up with these patients,” she said. “They’re just kind of lost in the wind. A lot of the filters are placed by the trauma surgeons initially when the patient comes for trauma, and then the patients are followed by primary care or some other service, so they’re not followed up properly.”
Removal of the device was attempted in 71 patients, but only 58 patients (9%) had the IVC filter successfully removed. Of the 13 failed attempts, the researchers noted that the filter was embedded in the IVC in eight patients and that the filter migrated to an abnormal position in two patients. In one patient, a clot presented in the filter, and in three patients, the filter was protruding through a blood vessel. Of the 13 unsuccessful retrievals, the IVC filter was in place for more than 85 days in 11 patients. One patient had the IVC filter removed after it was in place for more than five years.