By: Paul Ippolito, Rutgers New Jersey Medical School, 2020

Edited by: Giovanni Santoro, DO

Pulmonary embolism refers to an acute blockage or obstruction of a pulmonary artery by a thrombus formed at another anatomical site, commonly the deep veins of the legs, that has traveled to the lungs [1]. Inferior vena cava (IVC) filters are typically indicated for patients suffering from a pulmonary embolism or deep vein thrombosis when anticoagulation is contraindicated or has failed [2]. Temporary IVC filters are intended for short-term use, primarily to prevent pulmonary embolism in high-risk patients, or as secondary prevention after a venous thromboembolism [3]. A fundamental question underlying the use of temporary retrievable filters is whether they are safe and effective long-term. IVC filters are associated with rare peri-procedural and long-term complications such as filter fracture, filter migration, filter embolization, filter-caval penetration, caval thrombosis by the filter, and recurrent deep vein thrombosis [4,5]. The exact etiology of filter thrombosis is unknown. It may be related to increased baseline risk for thromboembolism, a captured thrombus, or to the filter’s inherent thrombogenicity as a foreign body in the vena cava. In August 2010, the Food and Drug Administration (FDA) reported 921 adverse event reports for IVC filters in the preceding 5 years including 328 device migrations, 146 embolizations, 70 IVC perforations, and 56 filter fractures [6]. Based off these findings, the FDA issued safety warnings calling for prompt retrieval of retrievable IVC filters once risk has abated or when anticoagulation is indicated. The FDA further suggested a removal window of 29 to 54 days after implantation [7].  Despite these recommendations, poor retrieval rates for IVC filters have been widely observed in health systems (10-33%), with rates improving in institutions with dedicated filter programs [8-14].

The present study evaluates national trends of IVC filter placement, repositioning, and retrieval rates during a 4-year period, within the Medicare population. This study included data from interventional radiologists, vascular and other surgeons, and interventional cardiologists.

Study Population, Methods, and Data Collection

In order to assess national trends regarding IVC filter placement, repositioning, and retrieval, the researchers used the Medicare Physician/Supplier Procedure Summary Master Files. These files pertain to Medicare Part B carriers and include information about fee-for-service claims for medical equipment such as IVC filters. Data was collected from 2012 through 2015, and the procedural codes for IVC placement, retrieval, and repositioning were used to calculate annual volume and rates per 100,000 Medicare beneficiaries using the Medicare Advantage State-County market penetration files. The results were outlined to determine whether the procedures were performed by radiologists, cardiologists, vascular and other surgeons.

Statistics & Results

Trends in performance of IVCF insertion and retrieval were compared among specialties. Within these conditions 95% confidence intervals were calculated. The IVCF placement rate decreased over four years from 156 procedures per 100,000 Medicare beneficiaries in 2012 (95% CI: 154.7 – 157.3) to 118 in 2015 (95% CI 116.9-119.1). IVCF retrieval rates increased from 11 procedures per 100,000 Medicare beneficiaries in 2012 (95% CI 10.7-11.3) to 16 in 2015 (95% CI 15.6-16.4). Radiologists were responsible for 60% of the total number of IVC filters placed and 63% of IVC filters retrieved from 2012 to 2015. This exceeded all other surgical specialties included in the study. Also, the ratio of filter removal procedures to placements across the entire Medicare fee-for-service population increased from 7% to 14%, and trends were similar across all surgical specialties. A Cochran Armitage nonparametric test was calculated for 4-year trends in filter placement and retrieval, and the values were significant (p < 0.0047). This test was used to determine the goodness-of-fit test for the linear model.

Conclusion

According to this study, IVCF retrieval rates increased while placement rates decreased among the Medicare fee-for-service population in the United States over a 4-year period. These findings are in line with the FDA’s call to reduce patient harm by improving filter retrieval. The methods used in this study might provide a direct understanding of the national trend, however, this study is limited in that it says little about non-Medicare beneficiaries. In addition to the inclusion of non-Medicare beneficiaries, future studies would also benefit from a longer study time and data on filter placement indications. One highlight of this study is that radiologists, compared to non-radiologists, placed and retrieved the majority of IVC filters. The study shows that Interventional Radiologists have increased ownership in this domain and are in the driver’s seat regarding appropriate filter utilization and patient follow-up.

References

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7. U.S. Department of Health and Human Services. Removing retrievable inferior vena cava filters: FDA Safety Communication. Updated May 6, 2014. Available http://www.fda.gov/MedicalDevices/Safety/ AlertsandNotices/ucm396377.htm. Accessed July 22, 2018.

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