National Trends in Inferior Vena Cava Filter Placement and Retrieval Procedures in the Medicare Population Over Two Decades

The development of a novel endovascular grasper for challenging inferior vena cava filter retrieval

OBJECTIVE

Although inferior vena cava (IVC) filters are commonly retrieved using a snare, lateral tilt and fibrosis around struts can complicate the procedure and sometimes require the use of off-label devices. We describe the development of a novel articulating endovascular grasper designed to remove permanent and retrievable IVC filters in any configuration.

METHODS

For in vitro testing, the IVC filters were anchored to the inner wall of a flexible tube in a centered or tilted configuration. A high-contrast backlit camera view simulated the two-dimensional fluoroscopy projection during retrieval. The time from the retrieval device introduction into the camera field to complete filter retrieval was measured in seconds. The control experiment involved temporary IVC filter retrieval with a snare. There were four comparative groups: (1) retrievable filter in centered configuration; (2) retrievable filter in tilted configuration; (3) permanent filter in centered configuration; and (4) permanent filter in tilted configuration. Every experiment was repeated five times, with median retrieval time compared with the control group. For in vivo testing in a porcine model, six tilted infrarenal IVC filters were retrieved with grasper via right jugular approach. Comparison analysis between animal and patient procedures was performed for the following variables: total procedure time, the retrieval time, and fluoroscopy time.

RESULTS

The in vitro experiments showed comparable retrieval times between the experimental groups 1, 2, and 4 and the control. However, grasper removal of a centered permanent filter (group 3) required significantly less time than in the control (29 vs 79 seconds; P = .009). In the animal model, all IVC filters were retrieved using the grasper with no adverse events. The total procedure time (21.2 vs 43.5 minutes; P = .01) and the fluoroscopy time (4.3 vs 10 minutes; P = .044) were significantly shorter in the animal model compared with the patient group. Moreover, in the patient group, 16.7% of retrievals required advanced endovascular techniques, and one IVC filter could not be retrieved (success rate = 91.7%), whereas all the IVC filters were successfully retrieved in the animal model without the use of additional tools.

CONCLUSIONS

The novel endovascular grasper is effective in retrieving different types of IVC filters in different configurations and compared favorably with the snare in the in vitro model. In vivo experiments demonstrated more effective retrieval when compared with matched patient retrievals.

Health Services Research: A Review for the Interventional Radiologist

Health services research (HSR) is a multidisciplinary field which studies access to drivers of health care service utilization, the quality and cost of services, and their outcomes on groups of patients. Since its foundations in the 1960s, there has been a large focus on HSR and using large data sets to study real-world care. Because interventional radiology (IR) is a dynamic field with foundations in innovation, research often focuses on small-scale projects. This review will discuss HSR including data sources, focus areas, methodologies, limitations, and opportunities for future directions in IR.

Epidemiology of the use of inferior vena cava filters in Brazil between 2008 and 2019

OBJECTIVES

The primary objective was to study the totality of inferior vena cava filter placements and their temporal and geographic distribution in the Brazilian Public Health System, which insures more than 160 million Brazilians. The secondary objective was to analyze in-hospital mortality after filter placement and deaths due to pulmonary embolism.

METHODS

Public and open data on in-hospital mortality due to pulmonary embolism and on rates of inferior vena cava filters placement, its associated diagnosis, and in-hospital mortality in Brazilian public hospitals between January 2008 and December 2019 were extracted from Ministry of Health databases.

RESULTS

A total of 9108 inferior vena cava filters were placed, 98.18% of which was therapeutic. We observed a significant increase in the use of these devices over the years, from 508 inferior vena cava filters placed in 2008 to 965 in 2019. In-hospital mortality rate in patients who received inferior vena cava filters was 6.21%, stable over time, and 96.64% of causes of these causes were attributed to venous thromboembolism. The in-hospital mortality rate due to pulmonary embolism, regardless of the placement of vena cava filters, has increased significantly.

CONCLUSION

We observed a low but increasing rate of inferior vena cava filter placements in Brazil between 2008 and 2019, most indications were therapeutic. Our findings were heterogeneous across Brazilian regions and contrasted to those observed in the USA, which is likely due to cultural and socioeconomic factors.

Inferior Vena Cava Filter Retrieval Rates Associated With Passive and Active Surveillance Strategies Adopted by Implanting Physicians

IMPORTANCE

Inferior vena cava filters are commonly implanted and infrequently retrieved. Nonretrieval contributes to significant morbidity, motivating US Food and Drug Administration and multisociety communications emphasizing the need for improved device surveillance. Current guidelines suggest that implanting physicians and referring physicians should be responsible for device follow-up, but it is not known whether shared responsibility contributes to lower retrieval.

OBJECTIVE

To determine if primary responsibility for follow-up care assumed by the implanting physician team is associated with increased device retrieval.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study examined a prospectively collected registry of patients with inferior vena cava filters implanted from June 2011 to September 2019. Medical record review and data analysis was completed in 2021. The study included 699 patients who underwent implantation of retrievable inferior vena cava filters at an academic quaternary care center.

EXPOSURES

Prior to 2016, implanting physicians had a passive surveillance strategy whereby letters highlighting indications for and the need for timely retrieval were mailed to patients and ordering clinicians. Starting in 2016, implanting physicians assumed active responsibility for surveillance, whereby candidacy for device retrieval was assessed periodically via phone calls and retrieval scheduled when appropriate.

MAIN OUTCOMES AND MEASURES

The main outcome was the odds of inferior vena cava filter nonretrieval. Within regression modeling of the association between the surveillance method and nonretrieval, additional covariates of patient demographics, concomitant malignant neoplasm, and presence of thromboembolic disease were included.

RESULTS

Of the 699 patients who received retrievable filter implants, 386 (55.2%) were followed up with passive surveillance, 313 (44.8%) with active surveillance, 346 (49.5%) were female, 100 (14.3%) were Black individuals, and 502 (71.8%) were White individuals. The mean (SD) age at filter implantation was 57.1 (16.0) years. Mean (SD) yearly filter retrieval increased following the adoption of active surveillance, from 190 of 386 (48.7%) to 192 of 313 (61.3%) (P < .001). Fewer filters were deemed permanent in the active group vs passive group (5 of 313 [1.6%] vs 47 of 386 [12.2%]; P < .001). Age at the time of implantation (OR, 1.02; 95% CI, 1.01-1.03), concomitant malignant neoplasm (OR, 2.18; 95% CI, 1.47-3.24), and passive contact method (OR, 1.70; 95% CI, 1.18-2.47) were associated with increased odds of filter nonretrieval.

CONCLUSIONS AND RELEVANCE

The findings of this cohort study suggest that active surveillance by implanting physicians is associated with improved inferior vena cava filter retrieval. These findings support encouraging physicians who implant the filter to take primary responsibility for tracking and retrieval.

Cost Burden and Cost Influencers of Inferior Vena Cava Filter Placement and Retrieval among Medicare Beneficiaries with Acute Venous Thromboembolism

PURPOSE

To examine the frequency, costs, and cost influencers of inferior vena cava filters (IVCFs) placements and retrievals among a national sample of patients using Medicare data.

MATERIALS AND METHODS

This retrospective cohort study used the U.S. Medicare 100% database, a nationally representative sample of all U.S. patients aged ≥65 years, from 2014 through 2020. Procedures and clinical characteristics were identified from the diagnosis and procedure codes on Medicare claims. Beneficiaries aged ≥65 years with newly diagnosed venous thromboembolism (VTE) were identified and followed to obtain data on IVCF placements and retrievals. Data on the costs of the index IVCF procedures and any subsequent IVCF placements and retrievals were obtained. Multivariate models were used to estimate the impact of patient and clinical characteristics on costs.

RESULTS

Among 501,216 patients with newly diagnosed VTE, 4,995 (1%) received an IVCF placement; of these, 1,215 (24.3%) had a retrieval procedure. Beneficiaries with IVCF placements and retrievals differed from a demographic and clinical perspective than from those without. Costs varied by the site of service, VTE acuity, and VTE type. Cost influencers included age, race, census region, service location, and VTE type.

CONCLUSIONS

IVCF placement costs were driven by baseline patient characteristics (age, race, geographic residence, acute VTE diagnosis, and inpatient site of service), whereas retrieval costs were driven by age and deep vein thrombosis diagnosis. Strategies to mitigate the retrieval costs or the need to retrieve IVCFs may reduce the overall cost burden of IVCFs.

Population-Based Disparities in Inferior Vena Cava Filter Procedures Among Medicare Enrollees With Acute Venous Thromboembolism

PURPOSE

Venous thromboembolism (VTE) imposes a significant clinical and financial burden on patients and society. Inferior vena cava filters (IVCFs) are considered for patients with absolute contraindications or failures of anticoagulation. However, studies examining the population-based disparities of IVCF placement and retrieval are limited. The association between patient and clinical characteristics in the likelihood of and time to IVCF placement and retrievals in a nationally representative cohort was examined.

METHODS

Medicare patients aged ≥65 years with index VTE claims between 2015 and 2018 were followed through 2019 to identify IVCF placements and retrievals. Rates were compared using survival analysis methods.

RESULTS

Of the 516,978 patients with VTE diagnoses, 5,864 (1.1%) had IVCFs placed, and 1,884 (32.1%) of those underwent retrieval procedures. Placement and retrieval rates varied significantly by demographics, comorbidity burden, and geographic region. From Cox regression, older age (hazard ratio [HR], 1.26; P < .0001), higher baseline comorbidity (Elixhauser) score (HR, 1.07; P < .0001), and outpatient (vs inpatient) site of VTE service (HR, 2.11; P < .0001) were associated with increased frequency of IVCF placement. The rate of retrieval was significantly lower for men (HR, 0.83; P = .0393), patients with higher comorbidity scores (HR, 0.95; P = .0037), and those with outpatient (vs inpatient) VTE sites of service (HR, 0.77; P = .0173). Neither facility- nor county-level characteristics were significantly associated with placements or retrievals.

CONCLUSIONS

This large cohort of Medicare beneficiaries with newly diagnosed VTE demonstrated inequities in IVCF placement and retrieval.

Pharmacological and interventional management of pulmonary embolism: where do we stand?

As the third most common cardiovascular disease, pulmonary embolism (PE) has an uptrending incidence and mortality, resulting in significant healthcare expenditure. Risk stratification of acute PE guides management. Although anticoagulation remains the cornerstone management, systemic fibrinolysis and targeted therapeutic approaches, catheter-directed thrombolysis and catheter-based embolectomy are available for high-risk patients. Life-threatening bleeding complications associated with systemic fibrinolysis have restricted its widespread implementation. Catheter-based techniques for intermediate high-risk categories were devised to reduce bleeding complications and improve outcomes. Catheter-directed thrombolysis helps minimize bleeding by way of direct drug delivery. Catheter-based embolectomy mechanically retrieves thrombi without using fibrinolytics. This focused review of medical and interventional management of acute PE provides a highlight of ongoing trials expected to add value to current practice.

Evaluation of Changing Vena Cava Filter Use and Inpatient Hospital Mortality from 2016-2019: A Single-Institution Quality Improvement Project

Objective

To evaluate the changing trends of vena cava filter (VCF) insertion and determine whether changes in VCF use affected inpatient mortality.

Patients and Methods

A quality improvement project at Mayo Clinic, Rochester, Minnesota, tracks the type and reason for VCF insertions from January 1, 2016, through December 31, 2019, to facilitate appropriate retrieval. The rate of VCF insertions was compared with inpatient mortality rates, normalized for patient volumes using the number of hospital inpatient discharges.

Results

A total of 698 VCFs were placed in 695 patients: 2016 (n=243), 2017 (n=156), 2018 (n=156), and 2019 (n=120). The rate of VCF insertions (per 1000 inpatient discharges) was 4.02 in 2016, 2.91 in 2017, 2.54 in 2018, and 1.93 in 2019. Mean ± SD age at placement was 62±16.4 years and 59.2% (413/698) were men. Most VCFs were retrievable (85.1%; 594/698) and were placed for treatment (78.4%; 547/698) indications (acute venous thromboembolism within 3 months). The rate of VCF insertions was compared with the inpatient mortality rate (per 100 inpatient discharges) and remained stable (1.83 in 2016, 1.79 in 2017, 1.83 in 2018, and 1.76 in 2019) despite the significant decline in VCF use.

Conclusion

Data from this quality improvement study demonstrate a reduction of more than 50% in the use of VCFs from 2016 through 2019 at a large academic hospital. These changes are difficult to attribute to any single change in clinical use and there was no appreciable increase in the inpatient hospital mortality rate associated with this decrease in VCF filter use.

Nationwide Trends in Catheter-Directed Therapy Utilization for the Treatment of Lower Extremity Deep Vein Thrombosis in Medicare Beneficiaries

PURPOSE

To determine overall and provider specialty trends in the use of catheter-directed therapy for lower extremity deep vein thrombosis (DVT) treatment in the Medicare population.

MATERIALS AND METHODS

Using data obtained from 2007-2017 Centers for Medicare & Medicaid Services 5% research identifiable files, all claims associated with acute and chronic lower extremity DVT were identified. The annual volume of 2 services-venous percutaneous transluminal thrombectomy (current procedural terminology [CPT] code 37187) and venous infusion for thrombolysis (CPT code 37201 from 2007 to 2012 and CPT code 37212 from 2013 to 2017)-was examined for trends in DVT intervention. Utilization rates based on region and the place of service were calculated. The results were further categorized based on primary operator type (radiology, cardiology, surgery, and other).

RESULTS

The total number of DVT interventions increased over time, with 4.27 service counts per 100,000 beneficiaries in 2007 increasing to 13.4 by 2017, a growth rate of 12.09%. Radiologists performed the majority of interventions each year, except in 2013, in which they performed 46.6% of interventions, whereas surgeons and cardiologists combined performed the other 53.4%. In 2017, radiologists performed 7.56 services per 100,000 beneficiaries, which was 56.8% of the total count, more than those performed by surgeons, cardiologists, and unspecified providers combined.

CONCLUSIONS

Catheter-directed therapy is increasingly being used for the treatment of DVT, with its use undergoing a nearly 12-fold increase from 2007 to 2017 in the Medicare population. Radiologists remained the dominant provider of these services throughout the majority of study period, with a relative reduction in market share from 72% in 2007 to 57% in 2017.

An expert spotlight on inferior vena cava filters

Introduction: Inferior vena cava (IVC) filters are mechanical filtration devices designed as an alternative to surgical ligation/plication of the IVC. Their use has been controversial, especially with the introduction of retrievable filters and expanded/prophylactic indications.Areas covered: Authors discuss the types of available IVC filters, indications for placement, evidence on their effectiveness in general and specific patient populations, procedural considerations, off-label use, complications, and filter retrieval. This review is based on manuscripts/abstracts published from 1960 to 2021 on venous thromboembolism and IVC filters.Expert opinion: Despite the limited data on their effectiveness and survival benefit, IVC filters continue to play an important role in the treatment of patients with venous thromboembolism (VTE) who cannot receive standard anticoagulation. There is no role of IVC filters in patients without VTE. While retrievable filters are desirable for short-term use, a dedicated team-based approach, and advanced training are required for their successful removal. Newer devices are promising in improving patient safety . The device manufacturers and regulatory agencies should consider specific approaches to track device-related adverse events. Population-based studies are required to establish optimal patient population who would benefit from these devices. .

Navigating inferior vena cava filters in invasive cardiology procedures: A systematic review

BACKGROUND

Transfemoral venous access (TFV) is the cornerstone of minimally invasive cardiac procedures. Although the presence of inferior vena cava filters (IVCFs) was considered a relative contraindication to TFV procedures, small experiences have suggested safety. We conducted a systematic review of the available literature on cardiac procedural success of TFV with IVCF in-situ.

METHODS

Two independent reviewers searched PubMed, EMBASE, SCOPUS, and Google Scholar from inception to October 2020 for studies that reported outcomes in patients with IVCFs undergoing TFV for invasive cardiac procedures. We investigated a primary outcome of acute procedural success and reviewed the pooled data for patient demographics, procedural complications, types of IVCF, IVCF dwell time, and procedural specifics.

RESULTS

Out of the 120 studies initially screened, 8 studies were used in the final analysis with a total of 100 patients who underwent 110 procedures. The most common IVCF was the Greenfield Filter (36%), 60% of patients were males and the mean age was 67.8 years. The overall pooled incidence of acute procedural success was 95.45% (95% confidence interval = 89.54-98.1) with no heterogeneity (I²  = 0%, p = 1) and there were no reported filter-related complications.

CONCLUSION

This systematic review is the largest study of its kind to demonstrate the safety and feasibility of TFV access in a variety of cardiac procedures in the presence of IVCF.

Current Controversies in Inferior Vena Cava Filter Placement: AJR Expert Panel Narrative Review

Despite inferior vena cava (IVC) filter practice spanning over 50 years, interventionalists face many controversies in proper utilization and management. This article reviews recent literature and offers opinions on filter practices. IVC filtration is most likely to benefit patients at high risk of iatrogenic pulmonary embolus during endovenous intervention. Filters should be used selectively in patients with acute trauma or who are undergoing bariatric surgery. Retrieval should be attempted for perforating filter and fractured filter fragments when imaging suggests feasibility and favorable risk-to-benefit ratio. Antibiotic prophylaxis should be considered when removing filters with confirmed gastrointestinal penetration. Anticoagulation solely because of filter presence is not recommended except in patients with active malignancy. Anticoagulation while filters remain in place may decrease long-term filter complications in these patients. Patients with a filter and symptomatic IVC occlusion should be offered filter removal and IVC reconstruction. Physicians implanting filters may maximize retrieval by maintaining physician-patient relationships and scheduling follow-up at time of placement. Annual follow-up allows continued evaluation for removal or replacement as appropriate. Advanced retrieval techniques increase retrieval rates but require caution. Certain cases may require referral to experienced centers with additional retrieval resources. The views expressed should help guide clinical practice, future innovation, and research.

Effect of a dedicated inferior vena cava filter retrieval program on retrieval rates and number of patients lost to follow-up

PURPOSE We aimed to assess the efficacy of a dedicated inferior vena cava (IVC) filter retrieval program on filter retrieval rates and number of patients lost to follow-up. METHODS A dedicated IVC filter retrieval program began in July 2016. This consisted of tracking all patients with retrievable filters placed by interventional radiology (IR). At the time of filter placement, patients were scheduled for a retrieval consult in the IR clinic. Any missed appointments were followed up by a physician assistant. The program was overseen by a single IR physician. To assess this program's efficacy, we reviewed the records of all patients who had retrievable IVC filters placed by IR nine months prior to and nine months after program initiation. Demographics and clinical factors were then collected and compared. A P value of < 0.05 was considered statistically significant. RESULTS Prior to the program, 76 patients (31 males, 45 females; mean age, 64.2 years) had retrievable filters placed; 75% were placed due to a contraindication to anticoagulation. From this group, five filters were removed (6.6%), 42 patients were lost to follow-up (55.3%), 22 patients died (29.0%), and seven filters were deemed permanent by a physician after placement (9.2%). All five retrievals were successful and no complications were reported. After program initiation, 106 patients (59 males, 47 females; mean age, 58.8 years) had retrievable filters placed; 75.5% were placed due to a contraindication to anticoagulation. In this group, 30 filters were retrieved (retrieval rate 28.3%), 17 patients were lost to follow-up (16%), 23 patients died (21.7%), 28 filters were deemed permanent by a physician after placement (26.4%), and decisions were still pending in eight patients (7.5%). One patient (3.3%) had a minor complication during filter retrieval. Initiation of a filter retrieval program increased our retrieval rate (6.6% vs. 28.3%; P < 0.001) and reduced the number of patients with filters that were lost to follow-up (55.3% vs. 16%; P < 0.001). CONCLUSION Dedicated filter retrieval program is effective in increasing filter retrieval rates and decreasing the number of patients lost to follow-up.

Evolving Use of fMRI in Medicare Beneficiaries

Using the Medicare Physician-Supplier Procedure Summary Master File, we evaluated the evolving use of fMRI in Medicare fee-for-service beneficiaries from 2007 through 2017. Annual use rates (per 1,000,000 enrollees) increased from 17.7 to 32.8 through 2014 and have remained static since. Radiologists have remained the dominant specialty group from 2007 to 2017 (86.4% and 88.6% of all services, respectively), and the outpatient setting has remained the dominant place of service (65.4% and 65.4%, respectively).

Contemporary management of chronic indwelling inferior vena cava filters

OBJECTIVE

Despite increasing retrieval rates of the inferior vena cava (IVC) filter, less than one-third are removed within the recommended timeline. Prolonged filter dwell times may increase the technical difficulty of retrieval and filter-related complications. We sought to evaluate the contemporary outcomes of patients with chronic indwelling IVC filters at a tertiary care center.

METHODS

A retrospective analysis was performed from August 2015 through August 2019 of all patients who were referred for removal of a prolonged IVC filter with a dwell time >1 year. Descriptive analysis was used to evaluate patients' characteristics and procedural outcomes, which were reviewed through electronic medical records. Data were expressed as median with interquartile range (IQR) or number and percentage, as appropriate.

RESULTS

A total of 47 patients were identified with a median filter dwell time of 10.0 years (IQR, 6-13 years); 34 patients underwent IVC filter removal, and 13 patients refused retrieval. The median age of patients was 54.9 years (IQR, 42.5-64.0 years); the majority were female (57%) and white (53%). The most common indication for filter placement was high risk despite anticoagulation (49%), followed by venous thromboembolism prophylaxis (21%). The majority of patients were symptomatic (72%). If symptomatic, the most common reason for retrieval was IVC penetration (94%), and the chief complaint was pain (56%). Retrieval success was 97%, with a median length of stay of 0 days. The majority of retrievals were performed through an endovascular approach (97%). There was one postprocedural complication (3%).

CONCLUSIONS

Despite prolonged dwell times, IVC filter retrieval can be performed safely and effectively in carefully selected patients at a tertiary referral center.

Interventional Radiology Therapy: Inferior Vena Cava Filter and Catheter-based Therapies

Endovascular management of pulmonary embolism can be divided into therapeutic and prophylactic treatments. Prophylactic treatment includes inferior vena cava filter placement, whereas endovascular therapeutic interventions include an array of catheter-directed therapies. The indications for both modalities have evolved over the last decade as new evidence has become available.

Changing National Medicare Utilization of Catheter, Computed Tomography, and Magnetic Resonance Extremity Angiography: A Specialty-focused 16-Year Analysis

To assess changing utilization of extremity angiography from 2001 to 2016, focusing on modalities and provider specialties. Medicare PSPS Master Files from 2001-2016 and POSPUF from 2016 were used to determine overall and specialty utilization of diagnostic catheter angiography (DCA), CT angiography (CTA), and MR angiography (MRA). From 2001 to 2016, extremity angiography increased from 1107 to 1590 extremities imaged per 100,000 beneficiaries, with rapid expansion of CTA (22 in 2001 to 619 in 2009; plateau of 645 in 2016), but declines in DCA (1039 to 914) and MRA (45 to 30). Over time, extremity angiography shifted from 94% DCA, 4% MRA, and 2% CTA to 58% DCA, 41% CTA, and 2% MRA. For radiologists, extremity angiography increased slightly (741 to 767) with increases in CTA (20 to 595) and large decreases in DCA (681 to 145), with MRA remaining low (40 to 27). Extremity angiography increased for cardiologists (197 to 349) and vascular surgeons (87 to 351), both overwhelmingly performing DCA. Radiologists' share of all extremity angiography shifted from 67% to 48%, with interventionalists (47%), generalists (43%), and abdominal radiologists (7.4%) providing most radiologist services in 2016. Throughout, radiologists were the dominant providers of CTA (89% to 92%) and MRA (89% to 90%). Extremity angiography utilization in Medicare beneficiaries increased nearly 50% from 2001 to 2016, largely related to CTA performed by radiologists. Of radiologists, interventionalists and generalists together render most services. Cardiologists and surgeons assumed a large share of DCA previously performed by radiologists.

Renal artery injury during inferior vena cava filter removal with endobronchial forceps

Retrieval of tip-embedded inferior vena cava filters using endobronchial forceps is a well-described technique. The tip of dorsally tilted filters may be in proximity to the right renal artery, increasing the risk of arterial injury during retrieval. We present one case that illustrates renal artery injury requiring emergent stent graft repair. The three subsequent cases illustrate techniques that avoid renal artery injury using a femoral and jugular approach with the assistance of an arterial fiducial wire. Renal artery injury is a potential complication during retrieval of filters using endobronchial forceps that can be prevented with careful planning.

Magnification Spot Radiographs Improve Assessment for Inferior Vena Cava Filter Fractures prior to Removal Compared to CT

PURPOSE

To determine if magnification spot radiographs acquired before attempting inferior vena cava (IVC) filter removal have value in the assessment for filter fractures.

MATERIALS AND METHODS

A retrospective review of complex IVC filter removals performed at a tertiary referral center from October 2015 to May 2017 was performed. Magnification spot radiographs (frontal and at least 2 oblique views) were obtained with the fluoroscopic unit in the procedure suite prior to venous access for filter removal. Patients were included in the study if a computed tomography (CT) scan of the abdomen/pelvis before filter removal was available. Ninety-six patients (47 women and 49 men) were included. Most removed filters were the Recovery/G2/G2X/Eclipse/Meridian (n = 28), the Günther Tulip (n = 26), and the Celect/Celect Platinum (n = 22). Blinded review of the pre-procedural CT scans and spot radiographs for the presence of filter fractures was performed by 2 interventional radiologists. Accuracy of each modality was assessed using the status of the explanted filter as the gold standard. Agreement between the 2 readers was assessed with the kappa statistic.

RESULTS

Fractures were present in 27 explanted filters (28%). Accuracy of CT was 88% and 68% for readers 1 and 2, respectively, which increased to 98% and 97% with magnification spot radiographs. The kappa statistic was 0.12 for CT and 0.97 for spot radiographs.

CONCLUSIONS

Magnification spot radiographs acquired before attempting IVC filter removal improve detection of filter fractures and agreement among interventional radiologists. Therefore, these should be performed routinely to allow for optimal treatment planning.

Diagnostic Radiologists' Participation in the American Board of Radiology Maintenance of Certification Program

OBJECTIVE. Physicians across specialties have expressed concerns about Maintenance of Certification (MOC) programs of American Board of Medical Specialties member boards, calling for research about MOC acceptance, adoption, and value. The purpose of this study was to characterize diagnostic radiologists' participation in the American Board of Radiology (ABR) MOC program, the framework for its new Online Longitudinal Assessment program. MATERIALS AND METHODS. Practicing U.S. radiologists were identified from the Centers for Medicare & Medicaid Services Physician and Other Supplier Public Use File. Corresponding ABR diplomate certification information was obtained through the ABR public search engine. Focused on diagnostic radiologists (defined as those whose only ABR certificate is in diagnostic radiology), MOC participation rates were calculated across various physician characteristics for those whose participation was mandated by the ABR (time-limited certificates) and for those whose participation was not mandated (lifetime certificates). RESULTS. Among 20,354 included diagnostic radiologists, 11,479 (56.4%) participated in MOC. Participation rates were 99.6% (10,058/10,099) among those whose MOC was ABR mandated and 13.9% (1421/10,225) among those whose participation was not mandated (p < 0.001). The rates of nonmandated participation were higher (all p < 0.001) for academic than for non-academic radiologists (28.0% vs 11.3%), subspecialists than for generalists (17.0% vs 11.5%), and those in larger practice groups (< 10 members, 5.0%; 10-49 members, 12.6%; ≥ 50 members, 20.7%). State-level rates of nonmandated participation varied from 0.0% (South Dakota, Montana) to 32.6% (Virginia) and positively correlated with state population density (r = 0.315). CONCLUSION. Although diagnostic radiologists with time-limited certificates nearly universally participate in MOC, those with lifetime certificates (particularly general radiologists and those in smaller and nonacademic practices) participate infrequently. Low rates of nonmandated participation may reflect diplomate dissatisfaction or negative perceptions about MOC.

Disparities over Time in Volume, Day of the Week, and Patient Complexity between Paracentesis and Thoracentesis Procedures Performed by Radiologists versus Those Performed by Nonradiologists

PURPOSE

To compare the disparities between the paracenteses and thoracenteses performed by radiologists with those performed by nonradiologists over time. Variables included the volume of procedures, the days of the week, and the complexity of the patient's condition.

MATERIALS AND METHODS

Using carrier claims files for a 5% national sample of Medicare beneficiaries from 2004 to 2016, paracentesis and thoracentesis examinations were retrospectively classified by physician specialty (radiologist vs nonradiologist), day of the week (weekday vs weekend), and the complexity of the patient's condition (using Charlson comorbidity index scores). The Pearson chi-square and independent samples t-test were used for statistical analysis.

RESULTS

Between 2004 and 2016, the proportion of all paracentesis and thoracentesis procedures performed by radiologists increased from 70% to 80% and from 47% to 66%, respectively. Although radiologists increasingly performed more of both services on both weekends and weekdays, the share performed by radiologists was lower on weekends. For most of the first 9 years across the study period, radiologists performed paracentesis in patients with more complex conditions than those treated by nonradiologists, but the complexity of patients' conditions was similar during recent years. For thoracentesis, the complexity of patients' conditions was similar for both specialty groups across the study period.

CONCLUSIONS

The proportion of paracentesis and thoracentesis procedures performed in Medicare beneficiaries by radiologists continues to increase, with radiologists increasingly performing most of both services on weekends. Nonetheless, radiologists perform disproportionately more on weekdays than on weekends. Presently, radiologists and nonradiologists perform paracentesis and thoracentesis procedures in patients with similarly complex conditions. These interspecialty differences in timing and complexity of the patient's condition differ from those recently described for several diagnostic imaging services, reflecting the unique clinical and referral patterns for invasive versus diagnostic imaging services.

In comparison with other abdominal imaging modalities, which radiologists interpret abdominal MRI?

PURPOSE

To assess subspecialty mix and case volumes of general and abdominal subspecialty radiologists interpreting abdominal MRI.

METHODS

The 2016 CMS Physician/Supplier Procedure Summary Master File was used to obtain billed counts of radiologist-interpreted abdominal fluoroscopy, US, CT, and MRI examinations. The CMS Physician and Other Supplier Public Use File was used to assess the subspecialty mix and case volume of the radiologists interpreting those examinations.

RESULTS

The fraction of all abdominal imaging examinations interpreted by generalists and abdominal subspecialty radiologists was 70.7% and 16.5% for fluoroscopy; 68.7% and 21.0% for US; 71.4% and 19.2% for CT; and 41.9% and 52.5% for MRI. In 2016, the fraction of general and abdominal radiologists interpreting > 50 fluoroscopy examinations on Medicare fee-for-service beneficiaries was 15.1% and 16.2%. For > 50 US examinations, the fraction was 61.5% and 60.5%; for > 50 CT examinations, 91.2% and 79.6%; and for > 50 MRI examinations, 4.0% and 28.5%. The fraction of abdominal imaging examinations interpreted overall by low-volume providers (those interpreting ≤ 50 examinations in 2016) was 59.5% for fluoroscopy, 17.5% for US, 6.3% for CT, and 50.6% for MRI.

CONCLUSION

Nationally, most abdominal fluoroscopy, US, and CT examinations are interpreted by general radiologists, who have similar annual volumes of these examinations as abdominal subspecialty radiologists. In contrast, most abdominal MRI examinations are interpreted by abdominal subspecialty radiologists, who attain considerably higher volumes. These findings have implications for workforce planning and abdominal imaging fellowship design to ensure their graduates are optimally prepared to contribute to their future practices.

Long-term computed tomography follow-up results of strut penetration of inferior vena cava filters

OBJECTIVE

This study aimed to investigate the incidence of inferior vena cava (IVC) filter strut penetration and risk factors of organ involvement.

METHODS

From June 2003 to August 2015, there were 138 patients with deep venous thrombosis who received an IVC filter. Among 104 patients who did not have the IVC filter retrieved, 66 had follow-up computed tomography and were included in this study. The IVC filters used were 21 Günther Tulip (Cook Medical, Bloomington, Ind), 26 Celect (Cook Medical), and 19 OptEase (Cordis Corp, Bridgewater, NJ) filters. Filter strut penetration was categorized by a previously published scale of grade 0 to grade 3, and organ involvement was specifically assessed. Multivariate analysis was used to identify risk factors for organ-involving strut penetration (grade 3).

RESULTS

The median age of the patients was 66 years (27-84 years), and 46% were male. Median computed tomography follow-up duration was 14 months (1-137 months). IVC strut penetration was detected in all patients. Grade 1, grade 2, and grade 3 were 29%, 36%, and 35%, respectively. The risk factor of grade 3 penetration was indwelling time ≥30 months on binary logistic regression analysis (odds ratio, 4.395; 95% confidence interval, 1.179-16.385; P = .027).

CONCLUSIONS

Regardless of type of IVC filter, the incidence of strut penetration was high. The risk of adjacent organ involvement increases over time. Retrievable IVC filters need close follow-up and retrieval as soon as they are no longer needed.

State-Level Variation in Inferior Vena Cava Filter Utilization Across Medicare and Commercially Insured Populations

OBJECTIVE. Recent research on inferior vena cava (IVC) filter utilization in the United States has largely focused on national aggregate Medicare datasets, showing recent declines. Whether these national Medicare trends are generalizable across regions and payer populations is unknown. We studied recent state-level variation in IVC filter utilization across both Medicare and private insurance populations. MATERIALS AND METHODS. Using large individual beneficiary claims-level Medicare research identifiable files and a proprietary U.S. research database of the commercially insured population, we identified all billed IVC filter placement procedures performed between 2009 and 2015. We compared population-adjusted utilization rates by state and payer type. RESULTS. Between 2009 and 2015, IVC filter utilization across the United States declined by 36.3% (from 177.9 to 113.3 procedures per 100,000 beneficiaries) in the Medicare population and by 26.6% (from 32.7 to 24.0 procedures per 100,000 beneficiaries) in the privately insured population. For the Medicare population, state-level utilization rates varied 5.2-fold, from 48.4 to 251.3 procedures per 100,000 beneficiaries in Alaska and New Jersey, respectively. For the private insurance population, rates varied 5.5-fold, from 10.8 to 59.5 procedures per 100,000 beneficiaries in Oregon and Michigan, respectively. Nationally, utilization in the Medicare population was 5.0 times higher than that in the private insurance population (range by state, from 2.0 times higher in Hawaii to 11.1 times higher in Utah). Despite the national decline, utilization in Medicare and private insurance populations increased in five and seven states, respectively. State-level IVC filter utilization rates for the Medicare population correlated strongly with those for the privately insured population (r = 0.74; p < 0.001). In both the Medicare and privately insured populations, utilization rates correlated moderately with beneficiary age (r = 0.44 and r = 0.50, respectively; p < 0.001 for both). CONCLUSION. IVC filter utilization rates vary dramatically by state and payer population, and they likely depend in part on the age of the covered population. To better identify demographic and socioeconomic drivers of utilization, future research should prioritize nonaggregate multipayer claims-level approaches.

Guidewire Loop Dissection Technique for Filter Strut Endothelialization

Complex inferior vena cava (IVC) filter retrieval was usually in need of advanced techniques. Filter strut endothelialization without tilt of the filter was still one of the challenges. Therefore, we would like to describe the guidewire loop dissection technique, which required no extra equipment, to solve problem. A 53-year-old male had IVC filter for 8 months. Venogram showed no tilt of the apex and endothelialization of struts. The hook was snared but the filter cannot be retrieved. A fine guidewire was then advanced and formed a loop between the strut and the caval wall. With traction applied, the guidewire peeled the struts off the caval wall, resulting in the dissection of strut endothelialization. In the end, the filter was retrieved without injuring IVC. This technique was a feasible option for such circumstance.

Retrievable inferior vena cava filters in neurosurgical patients: Retrieval rates and clinical outcomes

OBJECTIVE

To assess inferior vena cava (IVC) filter retrieval rates and clinical outcomes in neurosurgical patients and to determine patient characteristics associated with filter retrieval.

PATIENTS AND METHODS

This single-center retrospective study included 204 consecutive neurosurgical patients (120 men, 84 women; mean age 60 ± 13 years) who underwent retrievable IVC filter insertion between 1/2011-9/2013. Institutional IVC filter database review was used to identify demographic and clinical data, indication for IVC filtration, and IVC filter type. Patients were followed clinically by the neurosurgical, hematology, and interventional radiology services until removal or conversion to a permanent device. Measured outcomes included filter retrieval rates and parameters associated with device removal.

RESULTS

The majority of filters were placed for venous thromboembolism (200/204, 98%). Of 204 filters, 38(19%) were retrieved at median 186 days post-placement (range 3-665 days), 112(55%) converted to permanent devices, 44(22%) patients were deceased, and 10(5%) patients were lost to follow-up after transfer to an outside healthcare facility. Patients with subarachnoid hemorrhage (18% vs. 35%, p = 0.025) and malignancy (5% vs. 25%, p = 0.009) were less likely to have filters removed. Filter type (p = 0.475), gender (p = 0.221), neurosurgical procedure (p = 0.639), and insurance status (p = 0.207) did not demonstrate a significant association with filter retrieval.

CONCLUSION

IVC filter retrieval rates in neurosurgical patients are low despite tracking patients clinically in a multidisciplinary setting. Those neurosurgical patients with intracranial hemorrhage or malignancy requiring IVC filters have a lower likelihood of filter retrieval and may benefit from use of permanent devices.