Abstract
Objective
The utilization of inferior vena cava filters (IVCF) has evolved over time. We explored the indications, complications, and outcomes of patients undergoing IVCF placement.
Methods
We performed a single institution, retrospective review of CPT codes for IVCF placement between 2018 and 2022. Patient characteristics and location were collected. Indications for IVCF placement were categorized. Procedural details were noted and immediate and long-term complications. IVCF removal, total IVCF days, and removal complication were analyzed. Overall mortality, cause of death, and if death occurred the same admission were included.
Results
An analysis of 347 patients undergoing IVCF placement was performed. Mean patient age was 65 years-old (+/– 16 years), 167 patients (48%) were male, and 28% with current malignancy at time of IVCF placement. 8% of patients had prior DVT, 22% prior PE, 3% prior IVCF. 84% were inpatient on floors, 12% in the ICU, and 4% ambulatory. IVCF were typically placed prior to a surgery with contraindication to anticoagulation (41%), gastrointestinal bleed (15%), failure of anticoagulation (10%), brain bleed (9%), and during venous thrombectomy (8%). The operations included spine procedures (17%) other orthopedic procedures (19%), abdominal procedures (32%), and bariatric interventions (6%). Retrievable filters were placed in 99% of patients. Immediate postoperative complications occurred in 6% of patients. Worsening edema within the same admission, DVT, and filter strut migration in 12% of patients. 29% of patients underwent IVCF removal, of which 10 were unsuccessful and resulted in the filter remaining in place despite an attempt to retrieve it. All-cause mortality at any time point was 21%, with 42% of mortalities occurring during the same admission as the IVC filter placement. Of these mortalities, 4 (1.2%) were secondary to VTE complications. Mortality at 30 days was 8.3% and at 1 year was 15.7%. Death during the admission of IVC filter placement was positively correlated with older age (p = 0.010) and current malignancy was associated with higher mortality (OR 2.2, p < 0.001). Spine surgery patients were 3.8 times more likely to undergo IVCF removal (p = 0.002) as well as patients undergoing ambulatory IVCF placement (p = 0.001).
Conclusion
IVCF placement has utility in younger patients undergoing elective operations, particularly spine procedures, with contraindication to anticoagulation. Older patients and those with current malignancy are unlikely to benefit given the higher mortality.
Keywords
Article Highlights
Type of Research: Retrospective Cohort Study
Introduction
Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), is a disease process with high morbidity and mortality. 1 The incidence of first time VTE is only 0.1% of the general population.2,3 However, among patients who have first time VTE, there is 12% risk of mortality in the first month after diagnosis. 4 The standard of care for these patients is the use of anticoagulants. 5 Although anticoagulants are the first line treatment, there are a subgroup of patients where the use of anticoagulants is contraindicated, ineffective, or results in severe anticoagulant complications. For these patients, IVC filters have been used as an alternative to prevent PE, 6 even though filters themselves do not treat the DVT, and in some cases can be associated with recurrent DVT.7,8 The use of IVC filters is not without risks. Different types of filters have different degrees of complications associated with filter placement, the design of the filter itself, and their long-term use. 9 These complications include malposition, filter migration, caval thrombosis, filter fracture, and filter strut penetrating surrounding structures and organs.10,11 There is now a significant increase in both availability and placement of retrievable filters since – assuming the filters are removed according to their instructions for use (IFU) – they offer less risk of long-term filter complications. 12 However, even with this updated information, filters are still not strictly removed according to their IFUs, creating a risk for potential filter fracture or migration in these patients. As the understanding of the risks posed by the filters themselves evolved, the use of IVC filters has decreased, though filters are still routinely placed and often not removed according to their IFU. 13
There have been numerous studies assessing the outcomes of IVC filters, a recent systematic review concluded that a degree of skepticism still surrounds the safety and efficacy of routine IVC filter placement. 9 Studies have shown an increase in PE-free survival following IVC filter placement 14 as well as an overall decrease in mortality rate when specifically compared to patients admitted for VTE and CHF who did not receive an IVC filter. 15 However, other studies have not shown a mortality benefit incurred by patients undergoing IVC filter placement for PE at the 1-year mark and in fact showed increased mortality in patients who had undergone IVC filter placement at 30 days. 16 Additionally, the use of IVCF has been correlated with worse outcomes in patients with intracranial malignancies. In our study, we want to study the current practice of the IVC filter use and assess the safety and efficacy of their use. 17 For patients having retrievable filters, we investigated the rate of filter removal and how that relates to patient morbidity to assess if there was clinical benefit to IVC filter placement.
Methods
Study Design
This retrospective cohort study included patients who underwent IVCF placement from January 2018 to December 2022 at a high-volume United States academic health system using the CPT code 37191 to indicate IVC filter placement. This study was approved by our institutional review board (21-00617-MOD003) and all patient data used was subsequently deidentified.
Data Collection
Data was extracted through manual review of patient charts. Included within the analysis was a comprehensive set of variables to capture aspects of patient demographics, medical history, and clinical status. General demographic variables encompassed age, sex, and the presence of medical conditions such as diabetes mellitus (DM), hypertension (HTN), hyperlipidemia (HLD), obesity, smoking history, chronic obstructive pulmonary disease (COPD), coronary artery disease (CAD), peripheral artery disease (PAD), atrial fibrillation (Afib), heart valve replacement, prior or current malignancy, and hormone replacement therapy (Oral contraceptives, Estrogen/Progesterone), as well as the diagnosis of a hypercoagulable state. Focusing specifically on deep vein thrombosis and pulmonary embolism (DVT/PE), we considered demographic details such as prior DVT history, PE history, the type of former PE (segmental, subsegmental, saddle), the presence of a current/new DVT or PE at the time of IVCF placement, and information regarding the chronicity of anticoagulation (AC) therapy. The location of the patient within the health system at the time of filter placement (ICU, inpatient but not within an ICU, or ambulatory) was also assessed, as was the length of the ICU admission if applicable, and specific conditions like the need for vasopressors and intubation at the time of IVCF placement and prolonged intubation (defined as greater than 7 days). Indications for IVCF placement were carefully documented, including specific contraindications to AC (gastrointestinal bleed, brain bleed, IVCF placement at time of venous thrombectomy, failure of AC/worsening DVT/PE) and the need for surgery (spine, orthopedic other than spine, bariatric, neurosurgery/brain, ENT, urology, wound debridement, gastrointestinal, OBGYN, and other). The date of the surgery was recorded. To clarify, patients undergoing IVCF placement prior to a surgery were all patients with existing diagnosis of DVT/PE on AC. IVCF was placed in order to successfully hold AC prior to planned operation and in the postoperative period. Regarding the IVCF procedure, we recorded variables including the date of the procedure, the medical specialty implanting the filter (vascular surgery or interventional radiology), the brand or specific type of filter, and whether a retrievable or permanent filter was employed. Access site variables were noted, specifying whether the femoral vein or internal jugular vein (IJV) was used, as well as laterality (right or left). Furthermore, the performance of a thrombectomy at the time of IVCF placement was indicated, and if a thrombectomy was performed, it was categorized as mechanical or pharmaco-mechanical. Information related to the IVCF procedure and immediate postoperative complications, including complications within 30 days of surgery, was collected. This included data on the specific IVCF placement complications, such as bleeding, hematoma, infection, and DVT. The long-term outcomes of IVCF placement were also documented, including filter removal, complications during removal, filter strut migration, and overall outcomes for the patient population, including mortality. These variables collectively provided a comprehensive dataset to evaluate the outcomes and complications associated with IVCF placement within our study population.
Data Analyses
All data analysis was performed using pandas (version 2.2.2) from the Python Data Analysis Library. Odds ratios (OR) were utilized to show associations between binary variables, including mortality, IVCF removal, and IVCF complications. Statistical significance was determined with a p value less than 0.05. Descriptive statistics were utilized to calculate percentages and averages for cohort data.
Results
In total, 347 patients undergoing IVCF placement were included for analysis. The mean age of this cohort was 65 years-old (+/– 16 years), 167 patients (48%) were male, and 181 (52%) were female. Most common comorbidities within this cohort included hypertension (59%), hyperlipidemia (36%), obesity (34%), smoking history (30%), diabetes (29%), and current malignancy (28%) (Table 1). Time of vascular consultation for IVCF placement occurred during an admission on the hospital floors for 292 patients (84%) and in the intensive care unit (ICU) for 41 (12%). 14 cases (4%) of all IVCF within the cohort were scheduled as ambulatory procedures.
Patient Characteristics and Location of Medical Care at Time of Inferior Vena Cava Filter Placement.
Specifically, for VTE history within the cohort, 132 patients (38%) had prior DVT and 75 (22%) had prior PE (Table 2). Out of the 75 patients with prior PE, 46 patients (61% of the PE patients) also presented with concurrent lower extremity DVT. Additionally, for the prior PEs, 54% were segmental, 33% subsegmental, and 12% saddle PEs. 10 patients (3%) had a prior IVCF before the current procedure. 237 patients (68%) were diagnosed with a new DVT at time of IVF placement. 103 (30%) presented with a new PE, of which 68% were segmental, 19% subsegmental, and 12% were saddle PEs.
Venous Thromboembolism History and Current Deep Vein Thrombosis and Pulmonary Embolism Events at Time of Inferior Vena Cava Filter Placement.
The most common indication for IVCF placement was prior to another operative procedure that had a contraindication to anticoagulation (AC), for a total of 142 patients (41%) (Table 3). Within this cohort, the most common surgery planned was a general surgery other than bariatric surgery (46, 32%), followed by an orthopedic surgery other than spine surgery (27, 19%), spine surgery (24, 17%), and bariatric surgery (Table 4). Other indications for IVCF placement within the cohort are detailed within Table 3. 39 patients (11%) underwent IVCF placement at time of venogram with thrombectomy for DVT.
Clinical Indications for Patients Undergoing Inferior Vena Cava Filter Placement.
Type of Surgical Procedure Requiring Cessation of Anticoagulation and Inferior Vena Cava Filter Placement.
During IVCF placement, 99% of the filters utilized were retrievable. 293 filters (84%) were placed via femoral vein access, 35 (10%) via IJV access, 13 (4%) ia popliteal vein access, and 6 (2%) via access to the great saphenous vein (GSV). Of the 39 patients undergoing venous thrombectomy at time of IVCF placement, 24 cases (62%) utilized Angiojet (Boston Scientific Corporation, Marlborough MA), followed by Penumbra (Penumbra Inc, Alameda CA) (8,21%), and Inari ClotTriever (Inari Medical Inc, Irvine CA).
Within the immediate post-operative period, within 30 days of the procedure, 20 (6%) patients experienced a complication (Table 5). This included 3 episodes of bleeding from the access site, 3 hematomas, 7 superficial surgical site infections, and 7 new DVTs. Of the complications above, superficial bleeding and hematoma, were relatively mild complications, so overall approximately 4% of patients experienced a significant immediate complication after IVCF placement. Of the group experiencing filter placement complications, they were more likely to be of older age and have more comorbidities than patients who did not experience immediate complications. 43 patients (12%) experienced long term post-operative complications from IVCF placement. This included complaints of worsening edema, 18 worsening DVT, 19 and 1 occurrence of filter strut migration.
Immediate and Long-Term Postoperative Complications After inferior Vena Cava Filter Placement.
Out of 347 patients undergoing IVCF placement, 101 (29%) had the IVCF subsequently removed (Table 5). Of these removals, 10 patients (10%) experienced filter removal complications. This included 9 unsuccessful filter removals, where the filter was left in whole in the IVC. For one patient, the filter fragmented, which was complicated by IVC tear. This resulted in a retained piece of the filter in the IVCF and emergent covered stent graft deployment. Out of the cohort, 6 patient (2%) had an additional IVCF placed in the future.
Overall mortality within the cohort was 71 deaths (20%) (Table 6). Mean days from IVCF placement to death was 174 days (+/– 32 days, range 0–1335 days). None of the deaths were secondary to complications from IVCF placement. 4 (6%) of the deaths were secondary to VTE complications, all of which were due to PE. Out of the 71 total deaths, 30 (42%) occurred during the same admission as IVCF placement. Overall, 30-day mortality was 8.3% and one-year mortality was 15.75%. Looking at mortality risk, current malignancy was associated with a higher mortality after IVCF placement, with an odds ratio 2.2 (33% vs 15%, p < 0.0001). Additionally, older age was associated with higher mortality (p = 0.010) after IVCF placement. There was no association between mortality and the other demographic variables.
Mortality and Percentage of Deaths Secondary to Venous Thromboembolism Within the Cohort.
*Percentage calculated from number of overall mortality cases.
When looking at type of surgical procedure that required IVCF placement (Table 4), patients undergoing spine surgery had a significantly higher chance of undergoing IVCF removal (p = 0.002) than patients undergoing other surgical procedures. Spine surgery patients were 3.8 times more likely to undergo IVCF removal than the rest of the cohort. When comparing locations vascular was consulted for IVCF placement, ambulatory procedures were significantly associated with IVCF removal (odds ratio 2.6, 71% vs 27%, p = 0.001) than ICU and floor patients. There was no association between gender and IVCF removal (p = 0.556). There was also no significant difference in IVCF removal complications for female and male patients (p = 0.392).
Discussion
This retrospective study details 347 patients undergoing IVCF placement, typically temporary IVCFs, for various contraindications to AC which was mostly prior to another operative procedure, followed by GI bleed or worsening VTE despite AC. IVCF placement had low short term and long-term postoperative complication rates, however, despite temporary filters being placed, only 101 patients (29%) had the IVCF subsequently removed. Those undergoing spine surgery and ambulatory IVCF placement patients, were more likely to have IVCF removal once recovered than other patients. There was also 20% mortality rate within the cohort, with current malignancy and older age being significantly associated with death after IVCF placement. Ultimately, these findings support that IVCF placement has utility in younger patients undergoing elective operations, particularly spine procedures, with contraindications to anticoagulation. Older patients and those with current malignancy are unlikely to benefit given the higher mortality in these patient populations.
Low rate of temporary IVCF removal is unfortunately commonly seen in medical practice. 14 The IVCF removal rate of 29% within the cohort is like that of rates in related literature, with IVCF retrieval ranging from 1% to 64% of patients with a mean of 34%. 15 The main reason for lack of IVCF removal within our cohort and the general population is the lack of coordinated follow-up after filter placement and the lack of patient education on the benefits of filter removal if feasible.16,17 Focused efforts from both surgical and medical teams 20 and dedicated programs oriented towards monitoring patients undergoing temporary IVCF placement are required to result in improved retrieval rates.21,22 This includes prioritizing IVCF follow-up in hospital discharge planning, semi-automated filter tracking application, and more patient-targeted efforts such as increased patient education, phone calls, and letters. 23 The authors and the institution that this study was conducted utilized both calls to patients and communication/coordination with referring doctors in attempt to improve retrieval rates. Our findings on poor filter removal mirror those encounters at a large community hospital, where most IVC filters were not removed, raising the risk of filter-associated complications, and supporting the need for development of comprehensive guidelines addressing use of IVC filters, and post-insertion monitoring practices. 20
Patients undergoing spine surgery were 3.8 times more likely to follow up and undergo IVCF removal than patients undergoing other operative procedures requiring temporary AC cessation. We suspect these findings due to the known risk of major orthopedic procedures, including spine procedures, carrying a higher VTE rate than other operations.19,24 Furthermore, the risks of AC for spinal surgery patients are high including epidural hematoma and postoperative bleeding. 24 Likely spine surgeons, including orthopedic and neurosurgeons, are educating their patients better on the postoperative risk and benefits of IVCF placement and better referring them for IVCF removal once out of the post-operative window when AC would be unsafe. 25 The authors believe spine surgery patients were more likely to undergo retrieval due to the regularly scheduled follow up with their both their operating orthopedic surgeon and vascular surgeon. This ensures referral for IVC filter removal when no longer required. Additionally, the orthopedic procedure is a shorter contraindication for anticoagulation in comparison to other contraindications requiring filter placement. 21
Additionally, we noted patients undergoing ambulatory procedures were more likely to undergo IVCF removal than inpatient and ICU patients. We presume that this is due to ambulatory patients being healthier and more likely able to make it to follow up appointments to schedule IVCF removal than those undergoing inpatient procedures. This phenomenon of the healthier patients undergoing elective operations was noted during the recent COVID pandemic. 18
On the contrary, older patients and those with current malignancy had higher mortality rates after IVCF placement, and thus are unlikely to benefit from IVCF placement. VTE in cancer patients is strongly associated with poor prognosis. Of cancer patients diagnosed with VTE, 44% had distal metastasis and one-year and five-year mortality rates were 68% and 86% respectively versus 38% and 67% for those without VTE events. 26 The majority of these cancer patients have reported cause of death secondary to cancer progression (71%), as opposed to VTE events (9%). 27 Thus, in patients with far progressed, metastatic disease, with poor one year prognosis, it may not offer a significant risk benefit to undergo IVCF placement. We acknowledge, clinical judgement for each individual patient is required when deciding on pursuing IVCF placement.
Interestingly, women were more likely to have IVCF removal complications than men. Female gender had been previously associated in increased rates of embolization compared to men in a study of patients undergoing thrombolysis for acute iliofemoral DVT that were treated with adjunctive IVC filter placement. 28 However, increased complication rates with IVCF removal have not been previously reported. Further research with larger patient populations is warranted to further investigate this trend. Of note, while the use of filters has decreased over the last several years, many of them are not retrievable IVC filters. The FDA MAUDE database has displayed that retrieval IVC filters are associated with a greater risk of filter complications, mechanical or otherwise, as compared to permanent filters.22,23
This investigation on the utility and outcome of IVCF use is not without limitations. First, this is a retrospective cohort study, which limits follow up and identification of VTE and IVCF complications when compared to a prospective study. Furthermore, this is a single institutional study, which may limit generalizing the findings to the general population. In addition, a larger study with more patients, would result in a higher-powered study, which may ascertain further differences between the indications for IVCF placement and postoperative outcomes. Also, in terms of long-term post-operative complications, it is not possible to ascertain if patients experiencing worsening lower extremity edema was secondary to filter placement versus post-thrombotic syndrome, which is a known, common complication after DVT. 24 Post-thrombotic syndrome is estimated to occur in up to 50% of patients after DVT, reducing quality of life with symptoms of leg swelling, heaviness, pain, and chronic venous stasis changes. Further studies on IVCF use, how to improve temporary filter removal rates, and understanding which patients would not benefit from IVCF placement is required.
Conclusions
IVCF placement has utility in younger patients undergoing elective operations, particularly spine procedures, with contraindications to anticoagulation. Furthermore, ambulatory patients have higher chance of IVCF removal than those undergoing IVCF placement as inpatients. Older patients and those with current malignancy, are unlikely to benefit from IVCF placement given the higher mortality in these patient populations.
Footnotes
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.