Decreasing Utilization of Inferior Vena Cava Filters in Post-FDA Warning Era: Insights From 2005 to 2014 Nationwide Inpatient Sample

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.

Updated Trends in Inferior Vena Cava Filter Use by Indication in the United States After Food and Drug Administration Safety Warnings: A Decade Analysis From 2010 to 2019

BACKGROUND

Overall inferior vena cava filter (IVCF) utilization has decreased in the United States since the 2010 US Food and Drug Administration (FDA) safety communication. The FDA renewed this safety warning in 2014 with additional mandates on reporting IVCF-related adverse events. We evaluated the impact of the FDA recommendations on IVCF placements for different indications from 2010 to 2019 and further assessed utilization trends by region and hospital teaching status.

METHODS

Inferior vena cava filter placements between 2010 and 2019 were identified in the Nationwide Inpatient Sample database using the associated International Classification of Diseases, Ninth Revision, Clinical Modification, and Tenth Revision codes. Inferior vena cava filter placements were categorized by indication for venous thromboembolism (VTE) "treatment" in patients with VTE diagnosis and contraindication to anticoagulation and "prophylaxis" in patients without VTE. Generalized linear regression was used to analyze utilization trends.

RESULTS

A total of 823 717 IVCFs were placed over the study period, of which 644 663 (78.3%) were for VTE treatment and 179 054 (21.7%) were for prophylaxis indications. The median age for both categories of patients was 68 years. The total number of IVCFs placed for all indications decreased from 129 616 in 2010 to 58 465 in 2019, with an aggregate decline rate of -8.4%. The decline rate was higher between 2014 and 2019 than between 2010 and 2014 (-11.6% vs -7.2%). From 2010 to 2019, IVCF placement for VTE treatment and prophylaxis trended downward at rates of -7.9% and -10.2%, respectively. Urban nonteaching hospitals saw the highest decline for both VTE treatment (-17.2%) and prophylactic indications (-18.0%). Hospitals located in the Northeast region had the highest decline rates for VTE treatment (-10.3%) and prophylactic indications (-12.5%).

CONCLUSION

The higher decline rate in IVCF placements between 2014 and 2019 compared with 2010 and 2014 suggests an additional impact of the renewed 2014 FDA safety indications on national IVCF utilization. Variations in IVCF use for VTE treatment and prophylactic indications existed across hospital teaching types, locations, and regions.

CLINICAL IMPACT

Inferior vena cava filters (IVCF) are associated with medical complications. The 2010 and 2014 FDA safety warnings appeared to have synergistically contributed to a significant decline in IVCF utilization rates from 2010 - 2019 in the US. IVC filter placements in patients without venous thromboembolism (VTE) declined at a higher rate than VTE. However, IVCF utilization varied across hospitals and geographical locations, likely due to the absence of universally accepted clinical guidelines on IVCF indications and use. Harmonization of IVCF placement guidelines is needed to standardize clinical practice, thereby reducing the observed regional and hospital variations and potential IVC filter overutilization.

Outcomes of bellwether cases related to inferior vena cava filters in multidistrict litigations

OBJECTIVE

In the present study, we identified and reviewed the outcomes of bellwether cases related to inferior vena cava (IVC) filter multidistrict litigations (MDLs).

METHODS

The legal research database, LexisNexis (New York, NY), was used to identify all cases related to IVC filters. Cases unrelated to the MDLs were excluded. Court documents recording the proceedings for bellwether cases sent to jury trials were retrieved from the LexisNexis subsidiary, Law360. Data on plaintiffs, filter models, reported complications, filed claims, decision-making body, verdicts, and rewards were reviewed.

RESULTS

A total of 678 cases pertaining to IVC filters were found in the database, of which 12 were identified as bellwether cases for MDL. Of the 12, 2 (16.7%) were initially ruled in favor of the plaintiffs in jury trials, although the judgment for 1 of these was later vacated by a judge. The remaining 10 (83.3%) had been decided in favor of the manufacturers by judges and juries.

CONCLUSIONS

Verdicts in all bench trials were in favor of manufacturers, suggesting that judges perceived the presented complications by patients to be within the normal realm of the expected risk of IVC filter use. The findings from the present study have emphasized the treating physicians' legal responsibility to adequately warn patients of all the associated risks with IVC filters. The findings have also indicated that physicians can still be found liable in product liability cases directed at manufacturers. Physicians should continue to actively monitor patients to optimize the IVC retrieval windows.

Vena Cava Filters: Toward Optimal Strategies for Filter Retrieval and Patients' Follow-Up

Mortality rates associated with venous thromboembolism (VTE) are high. Inferior vena cava filters (IVCFs) have been frequently placed for these patients as part of their treatment, albeit the paucity of data showing their ultimate efficacy and potential risk of complications. Issues regarding long-term filter dwell time are accounted for in society guidelines. This topic has led to an FDA mandate for filter retrieved as soon as protection from pulmonary embolism is no longer needed. However, even though most are retrievable, some were inadvertently left as permanent, which carries an incremental lifetime risk to the patient. In the past decade, attempts have aimed to determine the optimal time interval during which filter needs to be removed. In addition, distinct strategies have been implemented to boost retrieval rates. This review discusses current conflicts in indications, the not uncommon complications, the rationale and need for timely retrieval, and different quality improvement strategies to fulfill this aim.

Temporal trends in vena cava filter implantation in public health system inpatients: an 11-year analysis of the largest city in Brazil

Background

Vena cava filter implantation is considered a simple procedure, which can lead to overuse and over-indication. It is nevertheless associated with short and long-term complications.

Objectives

The goals of this study were to evaluate rates of vena cava filter implantation conducted by Brazil’s Unified Public Health System, analyzing in-hospital mortality and migration of patients from other cities seeking medical attention in São Paulo.

Methods

This study analyzed all vena cava filter procedures conducted from 2008 to 2018 in the city of São Paulo and registered on the public database using a big data system to conduct web scraping of publicly available databases.

Results

A total of 1324 vena cava filter implantations were analyzed. 60.5% of the patients were female; 61.7% were under 65 years old; 34.07% had registered addresses in other cities or states; and there was a 7.4% in-hospital mortality rate.

Conclusions

We observed an increase in the rates of use of vena cava filters up to 2010 and a decrease in rates from that year onwards, which coincides with the year that the Food and Drug Administration published a recommendation to better evaluate vena cava filter indications.

Analysis of Costs and Payments for Inferior Vena Cava Filter Retrieval in the Medicare Population

Over the past decade, inferior vena cava (IVC) filter retrieval has been increasing, in part due to Food and Drug Administration recommendations and legal pressure. The costs and margin of IVC filter removal are poorly understood. Medicare claims data from 2016 for the 103 highest volume centers for IVC filter retrieval were examined. Pooled mean charges, costs, payments, and margin were calculated by institution. Mean ± SD charges, costs, and payments were $14,138.00 ± $8,400.48, $3,693.28 ± $2,294.27, and $1,949.82 ± $702.91, respectively. Average (range) margin was -$1,706.18 (-$7,509.93 to $362.77). The margin was negative in 99 of the 103 (96%) institutions evaluated. The most significant contributors to the total procedure cost were operating room, supplies, and recovery (44.5%, 23.5%, and 10.4%, respectively). While IVC filter retrieval is often medically indicated, it is typically associated with a financial loss under current reimbursement structure.

Stability of Retained Inferior Vena Cava Filter Fragments After Filter Removal

PURPOSE

To assess the stability and outcome of fractured inferior vena cava (IVC) filter fragments that are retained in patients after IVC filter removal.

MATERIALS AND METHODS

A retrospective analysis was conducted on all patients at a single tertiary referral center between May 2005 and June 2020 with fractured IVC filters where fragment(s) were retained after removal of the main filter body. IVC filter fragment stability was assessed by a clinician review of computed tomography images, chosen from available radiologic studies, to best visualize the fragments. Data collected included filter type, fragment location, duration of fragment follow-up, fragment stability in location, and further fragment fracture or clinical sequelae.

RESULTS

Seventy-seven patients with retained IVC filter fragment(s) after complex filter removal were identified. Of this, 37 patients (14 men, 23 women) were deemed to have adequate imaging follow-up to assess positional stability of the retained fragments, whereas the remainder were excluded from further analysis. Excluding fractured foot processes, 51 separate filter fragments were retrospectively identified and followed for a median duration of 726 days (interquartile range, 843 days; range, 28-3353 days). Filter designs producing the studied fragments included Celect, G2, Recovery, Günther, OptEase, Meridian, and G2X/Eclipse. In all, 50 of 51 (98%) fragments were found to be unchanged in position during their respective intervals of observation. One fragment displayed a rotational change without migrating from its original location. No further fragment fractures or clinical sequelae were observed among the group.

CONCLUSIONS

When asymptomatic, retained IVC filter fragments are predominantly stable and can be safely followed on an intermediate-term basis.

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. .

Impact of Advanced Technique on Improvement in the Retrievable Inferior Vena Cava Filter Retrieval Rate

BACKGROUND

It is recommended to remove retrievable inferior vena cava filters (r-IVCFs) when they are no longer needed because their presence may give rise to serious complications related to prolonged placement of the filter. An advanced filter retrieval technique may help improve the retrieval rate.Methods and Results:107 consecutive patients (mean age; 61±18 years, male 53%) in whom r-IVCF retrieval was attempted were prospectively enrolled between April 2012 and December 2018. The frequently used advanced techniques were sling technique and biopsy forceps dissection technique. Retrieval success was 75% with standard retrieval technique alone; however, the overall retrieval success rate improved to 98% with advanced techniques. We observed few serious complications related to the retrieval procedure. Logistic multivariate analysis identified prolonged indwelling time (P=0.0011) and embedded hook in the caval wall (P=0.0114) as independent predictors, and the cutoff value for the indwelling time for requirement of advanced technique was 80 days.

CONCLUSIONS

Advanced retrieval techniques helped improve the retrieval rate without serious complications. We may need to consider the referral of patients to centers with expertise in advanced retrieval techniques when the indwelling time is >80 days, and pre-retrieval CT image shows a hook embedded in the vessel wall.

Structured team-oriented program to follow patients after vena cava filter placement: a step forward in improving quality for filter retrieval

To reduce inferior vena cava filter (IVCF) related complications, retrieval is recommended whenever possible. Nevertheless, IVCF retrieval rates remain lower than expected, likely due to insufficient follow-up after placement. We evaluated the value of a structured program designed to follow patients by the interventional radiology team up to 5 months after IVCF placement. We prospectively enrolled 366 consecutive patients (mean age 64 ± 17 years; 201 men and 165 women) who benefited from IVCF between March 2015 and February 2020. The program consisted of advising the patient and clinicians to consider IVCF retrieval as soon as possible (standard workflow) and systematically planning an additional follow-up visit at 5-month. Clinical and technical eligibility, as well as technical success for retrieval (TSR) were evaluated. At 5-months, 38 (10.4%) patients were lost to follow-up, and 47 (12.8%) had died. Among survivors, the overall retrieval rate was 58%. The retrieval rates were 83% and 97% for the clinically eligible and technically eligible patients for retrieval, respectively. The 5-month visit enabled 89 additional retrievals (47.8%) compared to the standard workflow. No significant difference was seen in TSR before and after 5 months (p = 0.95). Improved patient tracking with a dedicated IVCF program results in an effective process to identify suitable patients for retrieval and drastically improves retrieval rates in eligible patients. Involving interventionalists in the process improved IVCF patient management.

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.

Prevalence and Characterization of Interaction of Retrievable Inferior Vena Cava Filters with the Spine in Patients Undergoing Complex Filter Removal

PURPOSE

To examine spinal interaction types and prevalence of inferior vena cava (IVC) filters in patients presenting for complex filter removal.

MATERIALS AND METHODS

The records of 447 patients presenting for complex removal of IVC filters were reviewed, including patient demographics, IVC filter dwell time, filter fracture status, and computed tomography (CT) evidence of filter interaction with the spine. Spinal interaction was defined as a filter strut touching or penetrating into the vertebral body or disc. Patients with evidence of filter penetration and spinal interaction had abdominal CT that preceded filter removal assessed by 2 interventional radiologists to categorize the type of spinal interaction, including bony reaction and osteophyte formation.

RESULTS

CT evidence of spinal interaction by the filter was found in 18% of patients (80/447). Interaction with the spine was more common in single point of fixation filters than filters with rails (P = .007) and was more likely in filters with round wires than flat wires (P = .0007). Patients with interaction had longer dwell times (mean [SD] 5.7 [4.46] y) compared with patients without interaction (mean [SD] 3.2 [3.85] y); this relationship was significant (P < .0001). Women were more likely than men to experience filter/spine interaction (P = .04). Filters with spinal interaction were more likely to be fractured (P = .001). Filter interaction was found in 38% (30/78) of patients with symptoms, including chest and back pain, compared with 14% (50/369) of patients without symptoms (P < .0001, odds ratio 3.99).

CONCLUSIONS

Retrievable IVC filters may interact with the spine. These interactions are associated with longer filter dwell times, female sex, and round wire filter construction.

Effect of scheduling inferior vena cava filter removal during the placement encounter on filter removal rate

OBJECTIVE

In the present study, we sought to determine whether early pre-emptive scheduling of inferior vena cava filter (IVCF) removal during the preoperative IVCF placement visit would affect the IVCF removal rate.

METHODS

All electronically documented IVCF placements at a single institution were reviewed from April 2015 to July 2019. The baseline characteristics included age, the clinical indications for IVCF placement, inpatient/outpatient status, and type of IVCF placed. Statistical analysis was performed using the χ² for discrete variables and the two-tailed paired t test for continuous variables.

RESULTS

A total of 599 patients (mean age, 68 years; 273 women and 326 men) had undergone technically successful IVCF placement. During the preoperative consent process for placement, 232 patients had been scheduled for IVCF removal within 3 months after placement. However, 367 patients had not been scheduled for removal at the preoperative consent process. The indications for placement included failure of anticoagulation, a contraindication to anticoagulation (eg, bleeding), preoperative prophylaxis, and others. Of the 232 patients scheduled for IVCF removal during preoperative consent for IVCF placement, 103 (44%) had undergone successful IVCF removal (mean interval from placement, 107 ± 100 days). Of the 367 nonscheduled patients, 89 (24%) had undergone successful IVCF removal (mean time, 184 ± 215 days). We found a significant improvement in the IVCF removal rate between the scheduled and nonscheduled patients (P < .0001). Three patients (all from the scheduled group) had a clot burden within the IVCF, which meant they were inappropriate for removal. These patients were rescheduled and had eventually undergone uncomplicated removal.

CONCLUSIONS

Scheduling IVCF removal during the placement encounter significantly increased the IVCF removal rate. This approach could be a viable option for institutions where clinic time and/or resources are limited or unavailable and for patients who have difficulty traveling for clinical evaluations.

Costs and complications of hospital admissions for inferior vena cava filter malfunction

OBJECTIVE

Inferior vena cava filter (IVCF) malfunction can result from penetration, fracture, or migration of the device necessitating retrieval. Endovascular and open retrieval of IVCF have been described in institutional series without comparison. This study examines national hospital admissions for IVCF malfunction and compares the outcomes of open and endovascular retrieval.

METHODS

The National Inpatient Sample database (2016-2017) was reviewed for admissions with International Classification of Diseases, Tenth Revision (ICD-10) codes specific for IVCF malfunction. All ICD-10 procedural codes were reviewed, and patients were divided based on open or endovascular IVCF retrieval. Patient characteristics, outcomes, and costs of hospitalization were compared between the two groups.

RESULTS

There were 665 patients admitted with a diagnosis of IVCF malfunction. Open IVCF retrieval was performed in 100 patients and endovascular removal in 90 patients. Of those undergoing open surgery, 45 patients (45%) required median sternotomy and 55 (55%) required abdominal surgeries. Most patients were white females with a mean age of 54.4 years (range, 49.3-59.6 years) with a history of deep venous thrombosis (55.3%) or pulmonary embolism (31.6%). Most patients with IVCF malfunction were treated in large (81.6%) or urban teaching (94.7%) hospitals situated most commonly in the South (42.1%) and Northeast (29.0%) with no difference in characteristics of the patients or the centers between the two groups. Patients undergoing open IVCF retrieval were more likely to undergo surgery on an elective basis compared with endovascular IVCF retrieval (75.0% vs 11.1%; P < .001). Open IVCF retrieval was associated with a higher likelihood of thromboembolic complication compared with endovascular retrieval (20% vs 0%; P = .04). There was a trend toward higher infectious complications and overall complications with endovascular removal, but this difference did not reach statistical significance. Open retrieval was associated with a mortality of 5.0% compared with no inpatient mortality with endovascular retrieval (P = .33). The mean hospital length of stay was no difference between the two groups. Open retrieval was associated with significantly higher hospital costs than endovascular retrieval ($34,276 vs $19,758; P = .05).

CONCLUSIONS

Filter removal for patients with IVCF malfunction is associated with significant morbidity and cost, regardless of modality of retrieval. The introduction of specific ICD-10 codes for IVCF malfunction allows researchers to study these events. The development of effective tools for outpatient retrieval of malfunctioning IVCF could decrease related hospitalization and have potential savings for the healthcare system.

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.

Spanish multicenter real - life registry of retrievable vena cava filters (REFiVeC)

Background

The treatment of venous thromboembolic disease the treatment of choice is systemic anticoagulation. However, the interruption of the inferior vena cava with filters has been recommended when anticoagulation fails or there is a contraindication. Due to the rising inferior vena cava filter (IVCF) complications, physicians are encouraged to retrieve them when there is no longer recommended. In daily practice, it may be a difficult close follow-up of these patients. In this study, the primary objective was to evaluate the IVCF retrieval rate of all implanted filters in a Spanish registry. Secondary objectives were to analyze the causes of failed retrieval, procedure-related complications, and outcomes at a 12-month follow-up.

Results

Three hundred fifty-six vena cava filters were implanted in 355 patients. The types of filter were: Gunther Tulip (Cook Medical) 160 (44.9%), Optease (Cordis) 77 (21.6%), Celect (Cook Medical) 49 (13, 7%), Aegisy (Lifetech Scientific) 33 (9.2%), Option ELITE (Argon Medical devices) 16 (4.4%), Denali filter (BD Bard) 11 (3.08%), ALN filter (ALN) 10 (2.8%).

Removal was achieved in 274/356 (76,9%). eighty-two (23,1%) IVCF were not retrieved due to the following: 41 (11,5%) patients required ongoing filtration, 24 IVCF (6,7%) patients died before retrieval, and 17 (4,7%) impossibility of retrieval because of a tilted and embedded filter apex. There were no major complications observed.

Conclusions

The global retrieval rate of IVCF was achieved in 76.9%, and the adjusted retrieval rate was of 94.15% with no major complications. IVCF tilting was associated with failure of filter removal in less than 5% of cases. This study demonstrates that the retrieval procedure of IVCF is controlled by the clinician and not by the interventional radiologist.

Inferior Vena Cava Filter Evaluation and Management for the Diagnostic Radiologist: A Comprehensive Review Including Inferior Vena Cava Filter-Related Complications and PRESERVE Trial Filters

Inferior vena cava filters are commonly encountered devices on diagnostic imaging that were highlighted in a 2010 Food and Drug Administration safety advisory regarding their complications from long-term implantation. The Predicting the Safety and Effectiveness of Inferior Vena Cava Filters (PRESERVE) trial is an ongoing after-market study investigating the safety and utility of commonly utilized filters in practice today. While most of these filters are safe, prompt recognition and management of any filter-associated complication is imperative to prevent or reduce the morbidity and mortality associated with them. This review is aimed at discussing the appropriate utilization and placement of inferior vena cava filters in addition to the recognition of filter-associated complications on cross-sectional imaging. An overview of the PRESRVE trial filters is also provided to understand each filter's propensity for specific complications.

Feasibility and Acute Safety Study of Radiofrequency Energy Delivery to the Vena Caval Wall via an IVC Filter in Swine

Retrievable inferior vena cava (IVC) filters are self-expanding metallic devices implanted in the IVC to prevent migration of thrombi from the deep veins of the legs and pelvis to the lungs. The risk of complications from the filters increases with duration of implantation, but retrieval may be difficult due to intimal hyperplasia around the components of the filter. In this study, the potential for delivery of radiofrequency (RF) energy to the IVC wall via the filter was investigated. IVC filters were deployed in 4 swine while attached to a snare connected to a 480 kHz RF generator. Energy ranging from 0 to 48 kJ was applied via the filter followed by re-sheathing and withdrawal of the filter while connected to a force measurement device. Resheathing forces for the 0-energy cohort and pooled data from the 6-24 kJ cohorts were 4.50±0.70 N and 4.50±0.75 N, respectively. Petechial hemorrhages and variable non-occlusive thrombi were noted in some cohorts including the 0-energy cohort, consistent with delivery and acute retrieval of an IVC filter. Histologically, the extent of RF-induced injury was subtle at 6 kJ with focal areas of homogenized collagen while the 12 kJ cohort showed segmental tissue charring with coagulation necrosis which was more extensive for the 24 kJ cohort. The 48 kJ energy caused more extensive and non-target organ damage. The study demonstrated feasibility of delivery of RF to the IVC wall via a deployed filter, supporting further study of the ability of local RF heating of the IVC wall to inhibit the neointimal hyperplasia or as an aid in retrieval.

The Clinical Rationale for the Sentry Bioconvertible Inferior Vena Cava Filter for the Prevention of Pulmonary Embolism

The Sentry inferior vena cava (IVC) filter is designed to provide temporary protection against pulmonary embolism (PE) during transient high-risk periods and then to bioconvert after 60 days after implantation. At the time of bioconversion, the device's nitinol arms retract from the filtering position into the caval wall. Subsequently, the stable stent-like nitinol frame is endothelialized. The Sentry bioconvertible IVC filter has been evaluated in a multicenter investigational-device-exemption pivotal trial (NCT01975090) of 129 patients with documented deep vein thrombosis (DVT) or PE, or at temporary risk of developing DVT or PE, and with contraindications to anticoagulation. Successful filter conversion was observed in 95.7% of patients at 6 months (110/115) and 96.4% at 12 months (106/110). Through 12 months, there were no cases of symptomatic PE. The rationale for development of the Sentry bioconvertible device includes the following considerations: (1) the period of highest risk of PE for the vast majority of patients occurs within the first 60 days after an index event, with most of the PEs occurring in the first 30 days; (2) the design of retrievable IVC filters to support their removal after a transitory high-PE-risk period has, in practice, been associated with insecure filter dynamics and time-dependent complications including tilting, fracture, embolization, migration, and IVC perforation; (3) most retrievable IVC filters are placed for temporary protection, but for a variety of reasons they are not removed in any more than half of implanted patients, and when removal is attempted, the procedure is not always successful even with advanced techniques; and (4) analysis of Medicare hospital data suggests that payment for the retrieval procedure does not routinely compensate for expense. The Sentry device is not intended for removal after bioconversion. In initial clinical use, complications have been limited. Long-term results for the Sentry bioconvertible IVC filter are anticipated soon.

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.

Trends in vena cava filter insertions and "prophylactic" use

BACKGROUND

Prophylactic vena cava filter (VCF) use in patients without venous thromboembolism is common practice despite ongoing controversy. Thorough analysis of the evolution of this practice is lacking. We describe trends in VCF use and identify events associated with changes in practice.

METHODS

Using the National Inpatient Sample, we conducted a retrospective observational study of U.S. adult hospitalizations from 2000 to 2014. Trends in prophylactic VCF insertion were analyzed both across the entire study population and within subgroups according to trauma status and type of concurrent surgery. Annual percentage change (APC) was calculated, and trends were analyzed using Poisson regression.

RESULTS

Among 461,904,314 adult inpatients (median [interquartile range] age, 58.1 [38.5-74.3] years; 39.6% male), the incidence of VCF insertion increased rapidly at first (from 0.19% to 0.35%; APC, 11.2%; 95% confidence interval [CI], 10.3%-12.2%; P < .001), then at a slower rate after the publication of the Prévention du Risque d'Embolie Pulmonaire par Interruption Cave 2 (PREPIC2) trial in 2005 (from 0.35% to 0.42%; APC, 4.4%; 95% CI, 2.8%-6.0%; P < .001), and it began decreasing after the 2010 Food and Drug Administration (FDA) safety alert (from 0.42% to 0.32%; APC, -5.5%; 95% CI, -6.5% to -4.6%; P < .001). The percentage of total VCFs that had a prophylactic indication increased quickly before publication of the PREPIC2 trial (APC, 19.5%; 95% CI, 17.9%-21.0%; P < .001), increased at a slower rate after publication in 2005 (APC, 4.4%; 95% CI, 2.6%-6.2%; P < .001), and dropped after the FDA safety alert, stabilizing at 18.5% for the last 3 years (APC, -0.3%; 95% CI, -2.2% to 1.7%; P = .8). Subgroups most associated with prophylactic VCF insertion were operative trauma (odds ratio [OR], 10.9; 95% CI, 10.2-11.7), orthopedic surgery (OR, 4.7; 95% CI, 4.3-5.2), and neurosurgical procedures (OR, 3.9; 95% CI, 3.6-4.2). All groups except orthopedic surgery experienced a deceleration in prophylactic VCF growth after the publication of PREPIC2. Meanwhile, the FDA safety alert was associated with a decrease in prophylactic VCF insertions for all groups except other major surgery.

CONCLUSIONS

Whereas publication of the PREPIC2 trial led to a deceleration in prophylactic VCF insertion growth, the FDA alert had a bigger impact, leading to declining rates of prophylactic VCF use. Further investigations of prophylactic insertion of VCF in trauma, orthopedic, and neurosurgical patients are needed to determine whether current levels of use are justified.

Inferior Vena Cava Filters: Current Indications, Techniques, and Recommendations

The vena cava filter (VCF) is intended to prevent the progression of deep venous thrombosis to pulmonary embolism. Recently, the indications for VCF placement have expanded, likely due in part to newer retrievable inferior vena caval filters and minimally invasive techniques. This article reviews the available VCFs, the indications for use, the techniques for placement, and possible outcomes and complications.

Inferior Vena Cava Filters: Current and Future Concepts

The inferior vena cava filter clinical environment is notable for the degree of controversy, uncertainty, and fear associated with these devices by both physicians and the public. This article reviews some of the more important current issues with these devices as well as emerging and future trends.