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Survival Effects of Inferior Vena Cava Filter in Patients with Acute Symptomatic
Venous Thromboembolism and a Significant Bleeding Risk
Alfonso Muriel, MSc David Jiménez, MD, Phd Drahomir Aujesky, MD Laurent
Bertoletti, MD Herve Decousus, MD Silvy Laporte, MD, Phd Patrick Mismetti, MD,
PhD Francisco J. Muñoz, MD Roger Yusen, MD Manuel Monreal, MD, PhD
PII: S0735-1097(14)01171-1
DOI: 10.1016/j.jacc.2014.01.058
Reference: JAC 19925
To appear in: Journal of the American College of Cardiology
Received Date: 28 September 2013
Revised Date: 10 December 2013
Accepted Date: 21 January 2014
Please cite this article as: Muriel A, Jiménez D, Aujesky D, Bertoletti L, Decousus H, Laporte S, Mismetti
P, Muñoz FJ, Yusen R, Monreal M, , Survival Effects of Inferior Vena Cava Filter in Patients with Acute
Symptomatic Venous Thromboembolism and a Significant Bleeding Risk, Journal of the American
College of Cardiology (2014), doi: 10.1016/j.jacc.2014.01.058.
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SURVIVAL EFFECTS OF INFERIOR VENA CAVA FILTER IN PATIENTS WITH
ACUTE SYMPTOMATIC VENOUS THROMBOEMBOLISM AND A SIGNIFICANT
BLEEDING RISK
Alfonso Muriel, MSc1*, David Jiménez, MD, Phd2*, Drahomir Aujesky, MD3, Laurent
Bertoletti, MD4, Herve Decousus, MD4, Silvy Laporte, MD, Phd4, Patrick Mismetti, MD,
PhD4, Francisco J. Muñoz, MD5, Roger Yusen, MD6, Manuel Monreal, MD, PhD 7, for the
RIETE investigators
1Biostatistics Unit, Ramón y Cajal Hospital and Instituto Ramón y Cajal de Investigación
Sanitaria IRYCIS, CIBERESP, Madrid, Spain.
2Respiratory Department, Ramón y Cajal Hospital and Instituto Ramón y Cajal de
Investigación Sanitaria IRYCIS, Madrid, Spain.
3Division of General Internal Medicine, Bern University Hospital, Bern, Switzerland.
4Thrombosis Research Group, EA3065, Université de Saint-Etienne, Jean Monnet, F-42023.
Inserm, CIE3. Service de Médecine Interne et Thérapeutique, Hôpital Nord, CHU de Saint-
Etienne, F-42055. Saint-Etienne, France.
5Department of Internal Medicine. Hospital de Mollet. Barcelona. Spain
6Divisions of Pulmonary and Critical Care Medicine and General Medical Sciences,
Washington University School of Medicine, St. Louis, Missouri, USA
7Department of Internal Medicine. Hospital Universitari Germans Trias I Pujol. Badalona,
Barcelona. Spain
*Both authors contributed equally to the manuscript.
ACKNOWLEDGEMENTS: We express our gratitude to Sanofi Spain for supporting this
Registry with an unrestricted educational grant. We also express our gratitude to Bayer
Pharma AG for supporting this Registry. Bayer Pharma AG’s support was limited to the part
of RIETE outside Spain, which accounts for a 18,19% of the total patients included in the
RIETE Registry. We also thank the Registry Coordinating Center, S & H Medical Science
Service, for their quality control, logistic and administrative support.
Conflict of interest statement: None reported
Correspondence:
David Jiménez Castro
Respiratory Department and Medicine Department
Ramón y Cajal Hospital, IRYCIS and Alcalá de Henares University
28034 Madrid, Spain
Phone: +34913368314
e-mail: djc_69_98@yahoo.com
Short title: Filters for VTE
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ABSTRACT
Objectives: The purpose of this study was to investigate the survival effects of inferior vena
cava filter in patients with venous thromboembolism (VTE) and a significant bleeding risk.
Background: The effectiveness of inferior vena cava filter use among patients with acute
symptomatic VTE and known significant bleeding risk remains unclear.
Methods: In this prospective cohort study of patients with acute VTE identified from the
RIETE registry, we assessed the association between inferior vena cava filter insertion placed
for known significant bleeding risk and the outcomes of all-cause mortality, pulmonary
embolism (PE)-related mortality, and VTE rates through 30 days after initiation of VTE
treatment. We used propensity score matching to adjust for the likelihood of receiving a filter.
Results: Of the 40,142 eligible patients that had acute symptomatic VTE, 371 underwent
filter placement because of known significant bleeding risk. Three hundred and forty four
patients treated with a filter were matched with 344 patients treated without a filter.
Propensity score-matched pairs showed a non-significant trend toward lower risk of all-cause
death for filter insertion compared with no insertion (6.6% vs. 10.2%, P = 0.12). The risk-
adjusted PE-related mortality rate was lower for filter insertion than no insertion (1.7% vs.
4.9%, P = 0.03). Risk-adjusted recurrent VTE rates were higher for filter insertion than no
insertion (6.1% vs. 0.6%, P > 0.001).
Conclusions: In patients presenting with VTE and a significant bleeding risk, compared to
anticoagulant therapy, IVC filter insertion was associated with a lower risk of PE-related
death, while it was associated with a higher risk of recurrent VTE. However, study design
limitations do not imply a causal relationship between filter insertion and outcome.
Key words: Venous thromboembolism; vena cava filter; survival; prognosis; pulmonary
embolism; deep vein thrombosis.
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INTRODUCTION
Despite the advances in the diagnosis and management of venous thromboembolism (VTE),
deep vein thrombosis (DVT) and pulmonary embolism (PE) remain a major cause of
morbidity and mortality (1). Conventional treatment for VTE consists of the use of parenteral
agents (i.e., unfractionated heparin (UFH), low-molecular-weight heparin (LMWH),
fondaparinux) as a “bridge” for oral anticoagulation therapy (2). Guidelines do not
recommend insertion of a filter in the inferior vena cava (IVC) as a primary treatment of
VTE. A large population-based retrospective analysis that assessed for recurrent VTE in
patients treated with an IVC filter for an acute VTE found that the use of a filter was
associated with a higher incidence of rehospitalization for venous thrombosis among patients
who initially manifested PE (3). Stein et al showed that all-cause in-hospital case fatality rate
was lower among unstable PE patients who received thrombolytic therapy and had a vena
cava filter (4). In the only clinical trial that evaluated the efficacy of vena cava filters (in
addition to standard anticoagulant therapy), this treatment reduced the risk of PE but
increased that of DVT and had no effect on survival (5). An 8-year follow-up of the patients
enrolled in the PREPIC trial showed similar results (6).
In the absence of randomized clinical trials that demonstrate a mortality benefit of IVC filter
treatment of VTE, the American College of Chest Physicians (ACCP) guidelines mainly
limit their recommendation for IVC filter insertion for patients with acute symptomatic VTE
and a contraindication to anticoagulation (Grade 1B) (2). Unfortunately, studies have not
clearly determined which patients with VTE would benefit from vena cava filter therapy.
Given the lack of data supporting a survival benefit of IVC filter therapy in patients with
acute VTE, we conducted this study of data collected for an international multicenter registry
(7, 8). The study assessed the association between the insertion of an IVC filter and mortality
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and other outcomes during the first month after treatment for an acute symptomatic VTE in
patients that had known significant bleeding risk.
METHODS
Study design
This retrospective study used prospectively collected data from patients enrolled in the
Registro Informatizado de la Enfermedad TromboEmbólica (RIETE registry) (7, 8). All
patients provided written or oral consent for participation in the registry in accordance with
local ethics committee requirements.
Study cohort and definition of treatment groups
At each participating site, RIETE investigators aimed to enroll consecutive patients that had
acute symptomatic or asymptomatic VTE confirmed by objective testing that consisted of
high probability ventilation-perfusion (V/Q) scintigraphy (9), positive contrast-enhanced, PE-
protocol, helical chest computerized tomography (CT) [single or multi-detector CT] for PE
(10), or lower limb venous compression ultrasonography positive for proximal DVT (11).
This study excluded those that had asymptomatic VTE. Of the patients treated with an IVC
filter, this study only included those patients that had an IVC filter inserted during the first 30
days after VTE diagnosis because of known significant bleeding risk (i.e., absolute or relative
contraindication to anticoagulation) determined by the local investigator (i.e., not
independently adjudicated).
For this study, we defined treated patients as those who received an inferior vena cava filter
(with or without concomitant anticoagulation) because of known significant bleeding risk.
We defined control patients as those with similar distributions of observed baselines
covariates (i.e., similar baseline risk of bleeding) to treated patients (see Statistical analysis),
who did not receive a filter but received anticoagulant therapy.
Baseline variables
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Patients enrolled in RIETE had data collected from around the time of VTE diagnosis that
included but was not limited to: age; gender; body weight; presence of coexisting conditions
such as chronic heart or lung disease; recent (<30 days prior to VTE) major bleeding;
presence of risk factors for PE including active cancer (defined as newly diagnosed cancer or
cancer undergoing treatment [i.e. surgery, chemotherapy, radiotherapy, hormonal, or support
therapy]), recent immobility (defined as non-surgical patients assigned to bed rest with
bathroom privileges for ≥4 days in the 2-months prior to VTE diagnosis), surgery (defined as
those who had undergone major surgery in the 2 months prior to VTE); clinical signs and
symptoms on admission, including heart rate and systolic blood pressure; and laboratory
results at hospital admission that included hemoglobin, platelet count and serum creatinine.
Study Outcomes
This study used all-cause mortality through 30 days after initiation of anticoagulant treatment
or filter insertion as the primary endpoint, and 30-day PE-related mortality, recurrent VTE,
and major bleeding as secondary endpoints. The RIETE investigators assessed mortality
presence, cause, and date using medical record review, and proxy interviews when necessary.
Clinicians at RIETE-enrolling sites managed patients with suspected recurrences according to
their local practice. Typically, the RIETE investigators defined recurrent DVT as a new
noncompressible vein segment, or an increase of the vein diameter by at least 4 mm
compared with the last available measurement on venous ultrasonography (12); recurrent PE
as a new ventilation–perfusion mismatch on lung scan or a new intraluminal filling defect on
spiral computed tomography of the chest) (10); and major bleeding episodes as those that
required a transfusion of at least 2 units of blood, were retroperitoneal, spinal or intracranial,
or were fatal (13).
Treatment and Follow-up
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Clinicians at RIETE-enrolling sites managed patients according to their local practice (i.e., no
standardization of treatment). In the RIETE registry, most patients received initial
anticoagulation with intravenous UFH or subcutaneous LMWH or fondaparinux, and overlap
and long-term therapy with an oral vitamin K antagonist. Clinicians administered
thrombolytic treatment and/or inotropic support as deemed appropriate. In general, clinicians
used thrombolytic treatment of acute PE in patients with cardiogenic shock (e.g., persistent
systolic arterial pressure of less than 90 mm Hg in the setting of clinical signs of organ
hypoperfusion [clouded sensorium, oliguria, cold and clammy skin, or lactic acidosis]).
RIETE recorded information related to patient outcomes through 3 months after the diagnosis
of the acute VTE, and this study analyzed outcomes through 30 days after initiation of VTE
treatment (i.e., anticoagulation or filter insertion).
Statistical analysis
We used chi-square or Fisher’s exact tests to compare categorical data between groups. We
used the Kolmogorov-Smirnov test to assess continuous data for a normal distribution. We
used two-tailed unpaired t-tests to compare normally distributed continuous data between two
groups, and we used the Mann-Whitney U test for non-normally distributed continuous data
comparisons. We used multivariate adjustment for age, cancer, recent or active bleeding,
immobilization, heart rate, systolic blood pressure, creatinine levels, platelet count, and
hemoglobin levels, via logistic regression to see if insertion of a filter was an independent
significant predictor of all-cause mortality in the entire sample (n = 40,142).
Since clinicians did not randomly allocate filter therapy, the patients who received an IVC
filter likely systematically differed from patients who did not with respect to baseline
characteristics, clinical course, clinical examination and test findings, and comorbid
conditions. We used a propensity score adjustment to compare treatment effects for patients
with similar predicted probabilities of receiving a filter (14). We used logistic regression to
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estimate propensity scores. We modeled the log odds of the probability that a patient received
a filter by using baseline demographic and clinical variables (see Baseline variables for
definitions) that were previously shown to be associated with mortality or treatment selection.
These variables included: patient age at time of diagnosis of VTE; presence or absence of
recent (<30 days prior to VTE) major bleeding; presence or absence of active bleeding at the
time of diagnosis of VTE; and presence or absence of risk factors for VTE that included
active cancer, or recent immobility; clinical signs and symptoms on admission, including
heart rate and systolic blood pressure; and anemia (defined as haemoglobin [Hb] < 13 g/dL in
men and Hb < 12 g/dL in women) (15), thrombocytopenia (platelet count < 100 x 109/L), and
abnormal serum creatinine levels (> 2 mg/dL).
After generation of the propensity scores, we sought to estimate the reduction in 30-day
overall mortality attributable to the insertion of a filter by using a greedy matched-paired
analysis that has a 1:1 matching algorithm and does not allow for replacements. We randomly
selected a patient in the treatment group and then matched that patient with the nearest patient
in the control group within a fixed caliper width of 0.05 (16). To assess the success of the
matching procedure, we measured standardized differences (measured in percentage points)
in observed confounders between the matched groups (17). We estimated the filter effect
using generalized estimating equation (GEE) methods to incorporate the matched-pairs
design, and adjusted for those covariates that remained unbalanced after matching (18). We
analyzed the data according to three different propensity-score models: one for any VTE, one
for symptomatic DVT (without symptomatic PE), and one for symptomatic PE. We
calculated the area under the curve (AUC) for each receiver operating characteristic (ROC)
curve to quantify propensity-score model accuracy and its ability to correctly discriminate or
identify the patients that received and those that did not receive an inferior vena cava filter.
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We performed several sensitivity analyses. First, we examined the effect of filters inserted
during the first 7 days after the diagnosis of VTE. Since most fatal PEs occurs within the first
few days after VTE diagnosis (8), we expected that the effectiveness of filters would be
greatest soon after the VTE diagnosis. Second, we evaluated various caliper widths iteratively
until between-group standardized differences were minimized. Finally, we repeated all
analyses for the secondary endpoints.
We used psmatch2 for the propensity score analyses, and we used Stata, version 11.2
(StataCorp, College Station, Texas) for Windows, for all other analyses.
RESULTS
We identified 40,975 patients with objectively confirmed VTE enrolled in RIETE during the
study period. After the exclusion of 230 (0.6%) patients with asymptomatic VTE, and 603
(1.5%) patients who received a filter for reasons other than a relative or absolute
contraindication to anticoagulation, the study cohort consisted of 40,142 patients with
confirmed DVT (51%), PE (32%), or both (17%) (Figure 1).
Unmatched cohort
Of the 371 patients who received an inferior vena cava filter, 152 (41%) had DVT (without
symptomatic PE), and 219 had PE (with or without symptomatic DVT). Patients treated with
filters and those treated without filters differed significantly in preexisting medical
conditions, or relevant clinical, physiologic and laboratory parameters (Tables 1 and 2).
Patients who received a filter had more comorbid diseases (cancer, recent surgery,
immobility, congestive heart failure, chronic lung disease, and recent bleeding), signs of
clinical severity (tachycardia and hypotension), and laboratory abnormalities (renal failure,
anemia, thrombocytopenia) compared to those that did not receive a filter.
Overall, 1,823 of 40,142 (4.5%) patients died (all-cause mortality) through 30 days after the
diagnosis of VTE. Three percent of the patients with DVT (602 of 20,503 patients) died
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during the 1-month study follow-up period, compared to 6.2% of the patients with PE (1,221
of 19,639 patients). Of the patients who received an inferior vena cava filter, 7.3% (27 of 371
patients) died during the 30-day study follow-up period. Of those who did not receive a filter,
4.5% (1,796 of 39,771 patients) died (absolute difference [AD] 2.8%; 95% confidence
interval [CI] of the AD, 0.5% to 5.9%; P = 0.02) during follow-up. Of the DVT patients
(without symptomatic PE) who received an inferior vena cava filter, 5.9% died during the
study follow-up period, compared to 2.9% of those who did not receive a filter (absolute
difference 3.0%; 95% CI of the AD, 0.2% to 8.0%; P = 0.05) during follow-up. Of the PE
patients, with or without DVT, who received an inferior vena cava filter, 8.2% died while 6%
of those who did not receive a filter died (absolute difference 2.0%; 95% CI of the AD, 0% to
6.4%; P = 0.28) during follow-up.
Matched cohort
The matching of patients presenting with any acute VTE yielded 344 patients treated with
filters and 344 patients treated without filters. This model showed good to excellent
discrimination with an AUC of 0.80. The standardized differences of less than 10% for all
matched variables supported the assumption of balance between treatment groups in observed
confounders (Table 3). We successfully matched 134 patients with acute symptomatic DVT
who received a filter with 134 patients who did not on the basis of propensity score (AUC,
0.87). The matching process eliminated some significant differences that existed between
groups regarding preexisting medical conditions, or relevant clinical, physiologic and
laboratory parameters (Table 4). Propensity analyses of the subgroup of patients with PE
used 210 matched pairs (210 patients from each group) (AUC, 0.74). The matched sample
showed good balance for each variable (Table 4).
Among those patients with DVT who did not have a filter, 128 received anticoagulant
therapy and 6 did not. Of the 128 anticoagulated patients with DVT, 121 patients (95%)
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received therapy with LMWH, 4 (3%) received UFH, and 3 (2%) received fondaparinux.
Among those patients with DVT who had a filter inserted, 80 received anticoagulants and 54
were not anticoagulated. Sixty-seven patients (84%) received therapy with LMWH, 12 (15%)
received UFH, and 1 (1%) received fondaparinux. Figure 2 shows LMWH dosing regimens
among matched patients who were treated with or without filters.
Among those patients with PE who did not have a filter, 200 received anticoagulant therapy
and 10 were not anticoagulated. Of the 200 anticoagulated patients with PE, 174 patients
(87%) received therapy with LMWH, 23 (12%) received UFH, and 3 (1%) received
fondaparinux. Among those patients with PE who had a filter inserted, 118 received
anticoagulants and 92 were not anticoagulated. Eighty-four patients (71%) received therapy
with LMWH, 31 (26%) received UFH, and 3 (3%) received fondaparinux. Figure 2 shows
LMWH dosing regimens among matched patients who were treated with or without filters.
Filter insertion was associated with a non-statistically significant lower mortality than non-
filter treatment in the matched cohort of patients with any VTE (6.6% vs. 10.2%; risk
difference, –3.6%; 95% CI, –7.7% to 0.7%; P = 0.12). A similar reduction in 30-day all-
cause mortality was evident for both subtypes of VTE (DVT and PE) (Table 5). Analysis of
propensity score-matched pairs (n = 344 pairs) showed a statistically significant decreased
risk of PE-related mortality for filter insertion compared with no insertion (1.7% vs. 4.9%;
risk difference, -3.2%; 95% CI, -6.2% to -0.5%; P = 0.03) (Table 5).
After propensity-score matching, there was no significant difference in the rate of major
bleeding at 30 days between patients receiving filters and those not receiving filters (3.8% vs.
5.2%; risk difference, –1.4%; 95% CI, –1.7% to 4.5%; P = 0.35) (Table 5). This difference
was also non-statistically significant in the matched cohort of patients who initially
manifested PE (3.8% vs. 6.7%; risk difference, –2.9%; 95% CI, –1.4% to 7.2%; P = 0.18). In
the subgroup of patients with DVT, the number of events did not allow for comparisons.
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The rates of recurrent VTE at 30 days in the matched cohort of patients with any VTE were
significantly higher among patients receiving filters than among those not receiving filters
(6.1% vs. 0.6%; risk difference, 5.5%; 95% CI, 2.8% to 8.2%; P < 0.001). Of the 21 recurrent
events that occurred in patients who received a filter, 15 (71%) were DVT and 6 (29%) were
PE. Two patients who did not receive a filter experienced a PE recurrence during follow-up.
In the matched cohort of patients with PE, recurrent VTE rate was significantly higher in
those patients who received a vena cava filter versus those that did not (8.1% vs. 1.0%; risk
difference, 7.1%; 95% CI, 3.2% to 11.0%; P < 0.001). In the subgroup of matched patients
with DVT, the number of events did not allow for comparisons.
Sensitivity analyses
When we evaluated filters inserted during the first 7 days after the diagnosis of VTE, results
mimicked the findings of the primary analysis: mortality rates in the group receiving filters
tended to be lower than those in the group not receiving filters, while VTE recurrences were
significantly higher. Similarly, we found consistent results when we evaluated various caliper
widths (0.1 SD and 0.2 SD).
DISCUSSION
Uncertainty surrounding the efficacy of IVC filters exists. The results of our study show that
in patients with significant bleeding risk, compared to anticoagulant therapy, filter insertion
was associated with a lower risk of 30-day PE-related mortality, while it was associated with
a higher risk of recurrent VTE. IVC filter therapy had a similar effect on each of the study
endpoints in the subgroups of patients who presented solely with DVT or with PE (with or
without DVT). However, study design limitations do not imply a causal relationship between
filter insertion and outcome.
Despite the relatively frequent use of IVC filters, few prospective randomized controlled
trials have assessed their efficacy and safety in patients with acute symptomatic VTE (19).
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Decousus et al evaluated the efficacy of permanent vena cava filters in the Prévention du
Risque d’Embolie Pulmonaire par Interruption Cave study, in which 400 patients with
proximal DVT were randomly selected to receive a permanent vena cava filter (5, 20). The
study also randomized patients to one of two classes of anticoagulants. The study did not
detect a difference in the death rate at any time during follow-up, comparing those with and
without vena filters (5, 20). Permanent filters reduced the risk of PE but increased the risk of
DVT (5). Although this study provided helpful information, it did not address the value of
IVC filters versus anticoagulant therapy in those situations in which filters are commonly
advocated (i.e., absolute contraindication to anticoagulation).
Many studies have demonstrated the relative efficacy and safety of standard anticoagulant
therapy in hemodynamically stable patients with PE. For patients with VTE and known
significant bleeding risk, this study suggested that use of an IVC filter, compared to
anticoagulant treatment, was associated with fewer deaths attributable to PE. Patients treated
with an IVC filter did not receive anticoagulation or received lower doses of anticoagulants
than those not treated with a filter. Thus, filter insertion may have prevented some fatal PE
recurrences. However, the IVC filter group had a higher rate of recurrent symptomatic VTE
in comparison to the non-filter group. Lack of anticoagulant treatment or thrombosis at the
filter site may have caused the higher recurrent DVT rate. Contrary to what might have been
expected, IVC filters increased the rate of symptomatic PE recurrence. Since patients treated
with an IVC filter had a lower PE-related mortality than those not treated with a filter, we
speculate that filters did not allow large PE to recur.
The risk of bleeding and other variables in an individual patient should lead to tailoring of the
intensity and type of treatment of symptomatic VTE (21). In this study, clinicians withheld or
used lower doses of anticoagulants in patients treated with an IVC filter, and this approach
had a non-statistically significant lower 30-day major bleeding rate compared to standard
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anticoagulation. These findings occurred even though the filter-treated subgroup had more
risk factors for bleeding than the anticoagulated cohort. Predicting which patients will have
major bleeding during anticoagulant therapy after VTE remains difficult. Researchers have
developed decision tools to better define the risk of anticoagulant-associated bleeding (22-
24). To find out whether such models can help clinicians decide which treatment option(s) to
choose will require further prospective studies in various at-risk groups.
Using data from the Nationwide Inpatient, Stein et al reported decreased case fatality rate
with vena cava filters in unstable patients, whether or not they received thrombolytic therapy,
and in stable patients who received thrombolytic therapy (4). But as far as we are aware, no
other population-based study has reported on the effectiveness of IVC filter use as an acute
management strategy for patients with acute VTE and known significant bleeding risk.
According to a Scientific Statement from the American Heart Association (25), adult patients
with any confirmed acute PE (or proximal DVT) with contraindications to anticoagulation or
with active bleeding complication should receive an IVC filter. Results of the present
investigation support this recommendation. An ongoing multicenter randomized trial, the
Prevention of Embolic Recurrences by Caval Interruption (PREPIC II) study
(NCT00457158), aims to determine the efficacy and safety of insertion of an inferior vena
cava filter in the prevention of the recurrence of PE (26).
Our findings should be interpreted in the context of our study design and its limitations.
Selection bias could have skewed the study sample. However, the broad range of patients
with acute symptomatic VTE from multiple medical centers, countries, and treatment settings
enrolled in the RIETE registry decreased the likelihood of the inclusion of a skewed
population in this study. The population-based sample we used described the effects of filters
in “real world” clinical care and enhanced the generalizability of the findings. Confounding
may have affected the results of this observational study. We used propensity-score matching
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to make the patient groups comparable according to the measured confounders (i.e., baseline
risk of bleeding), and we successfully eliminated the observed differences. However, residual
confounding may still have occurred. The similar results from many of the sensitivity and
secondary analyses provided evidence of the robustness of the findings and further
strengthened the soundness of the conclusions. Despite the large number of patients assessed
for this study from the RIETE registry, the relatively small sample size of the propensity-
matched cohorts lowered the statistical power of the study and therefore raised the chance
that the study would not detect a statistically significant difference in outcomes between the
treatment groups (i.e., type II error). Finally, concomitant anticoagulation might have
accounted for some of the differences between the groups' outcomes. However, since
clinicians typically use lower doses of anticoagulants in patients with high-risk of bleeding,
the study findings suggest that the design might have caused a slight bias against filter
insertion.
In conclusion, in patients with acute symptomatic VTE and known significant bleeding risk,
IVC filter therapy may reduce the risk of PE-related mortality compared to anticoagulant
therapy. However, lack of anticoagulation or thrombosis associated with IVC filters may
increase the risk of recurrent VTE. Randomized controlled trials of retrievable filters might
help to identify subgroups of patients at high risk of death that might have a favorable risk to
benefit ratio for treatment with filter insertion.
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24. Ruız-Gimenez N, Suarez C, Gonzalez R, Nieto JA, Todolí JA, Samperiz AL, Monreal
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Figure legends
Figure 1. Patient Flow Diagram.
Figure 2. LMWH dosing regimens. LMWH dosing regimens among matched patients with
DVT (A) or PE (B) who were treated with or without an inferior vena cava filter.
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Table 1. Clinical characteristics of patients with deep vein thrombosis who did or did
not receive a filter
Received filter
N = 152
Did not receive
filter
N = 20,351
P value
Clinical characteristics,
Age, years (mean + SD) 69.3 + 14.8 63.7 + 17.9 < 0.001
Age > 80 years 38 (25.0%) 4009 (19.7%) 0.12
Male gender
86 (56.6%)
10589 (52.0%)
0.30
Weight, kilograms (mean + SD) 71.3 + 15.8 74.3 + 15.0 0.01
Risk factors for VTE,
History of VTE 11 (7.2%) 3318 (16.3%) < 0.01
Cancer
60 (39.5%)
4283 (21.0%)
< 0.001
Recent surgery
4
0 (26.3%)
2162 (10.6%)
< 0.001
Immobilization for > 4 days 87 (57.2%) 4969 (24.4%) < 0.001
Comorbid diseases,
Chronic lung disease (4,894) 10 (15.6%) 1678 (34.7%) < 0.01
Chronic heart disease (4,360)
10 (15.9%)
838 (19.5%)
0.57
Recent major bleeding
72 (47.4%)
360 (1.8%)
< 0.001
Antiplatelet therapy (18,685) 17 (12.7%) 2080 (11.2%) 0.69
NSAIDs (18,670) 7 (5.2%) 1015 (5.5%) 0.90
Clinical symptoms and signs at
presentation
Heart rate
>
110/minute
13 (8.6%)
848 (4.2%)
0.01
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Arterial oxyhemoglobin saturation
(SaO2) < 90% (3,036)
3/30 (10%) 229/3006 (7.6%) 0.89
SBP < 100 mm Hg
7 (4.6%)
541 (2.6%)
0.22
Laboratory findings
Abnormal creatinine levels
(> 2 mg/dL)
39 (25.6%) 2565 (12.6%) < 0.001
Thrombocytopenia (< 100 x 10
9
/L)
14 (9.2%)
511 (2
.5%)
< 0.001
Hemoglobin, g/dL (mean
+
SD)
11.1
+
2.4
12.9
+
2.1
< 0.001
Abbreviations: SD, standard deviation; VTE, venous thromboembolism; NSAID, non-
steroidal anti-inflammatory drugs; SBP, systolic blood pressure.
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Table 2. Clinical characteristics of patients with pulmonary embolism who did or did
not receive a filter
Received filter
N = 219
Did not receive
filter
N = 19,420
P value
Clinical characteristics,
Age, years (mean + SD) 68.5 + 14.3 67.9 + 16.7 0.60
Age > 80 years 50 (22.8%) 5134 (26.4%) 0.26
Male gender 108 (49.3%) 8936 (46.0%) 0.27
Weight, kilograms (mean
+
SD)
73.2
+
15.2
74.7
+
15.3
0.15
Risk factors for VTE,
History of VTE 23 (10.5%) 2866 (14.7%) 0.09
Cancer 81 (37.0%) 4151 (21.4%) < 0.001
Recent surgery
34 (15.5%)
2352 (12.1%)
0.15
Immobilization for
>
4 days
85 (38.8%)
4676 (24.1%)
< 0.001
Comorbid diseases,
Chronic lung disease (6,557) 20 (30.8%) 2662 (41.0%) 0.12
Chronic heart disease (5,989) 11 (17.7%) 1700 (28.7%) 0.08
Recent major bleeding
70 (32.0%)
36
2 (1.9%)
< 0.001
Antiplatelet therapy (18,656)
32 (15.4%)
2928 (15.9%)
0.95
NSAIDs (18,638) 7 (3.4%) 945 (5.1%) 0.33
Clinical symptoms and signs at
presentation
Syncope
48 (21.9%)
2919 (15.0%)
< 0.01
Chest pain
102 (46.6%)
9211 (47.4%)
0.85
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Dyspnea 170 (77.6%) 15706 (80.9%) 0.26
Heart rate
>
110/minute
48 (21.9%)
4022 (20.7%)
0.72
Arterial oxyhemoglobin saturation
(SaO2) < 90% (13977)
55 (37.2%)
4140 (29.9%)
0.07
SBP < 100 mm Hg 30 (13.7%) 1488 (7.7%) < 0.01
Laboratory findings
Abnormal cr
eatinine levels
(> 2 mg/dL)
39 (17.8%)
3442 (17.7%)
0.97
Thrombocytopenia (< 100 x 10
9
/L) 15 (6.8%) 409 (2.1%) < 0.001
Hemoglobin, g/dL (mean + SD) 12.0 + 2.2 13.0 + 2.0 < 0.001
Abbreviations: SD, standard deviation; VTE, venous thromboembolism; NSAID, non-
steroidal ani-inflammatory drugs; SBP, systolic blood pressure.
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Table 3. Patient characteristics at cohort entry, before and after matching
Before matching After matching
Variable No filter
(n = 39,771)
Filter
(n = 371)
Standardized
difference
(%)
No filter
(n = 344)
Filter
(n = 344)
Standardized
difference
(%)
Venous thromboembolism
Demographic
Age (yr), mean (SD) 65.7 (17.5) 68.9 (14.5) 19.5 69.8 (15.3) 69.1 (14.2) 4.8
Comorbidities, %
Cancer 21.2 38.0 37.4 34.6 36.6 4.2
Im
mobilization
24.3
46.4
47.5
45.3
45.6
0.6
Recent or active bleeding 1.6 35.3 96.5 33.7 33.4 0.6
Physical exam
Heart rate (bpm), mean (SD) 87 (19) 91 (19) 21.5 91 (20) 95 (19) 1.0
SBP (mm Hg), mean (SD) 131 (23) 127 (24) 16.8 128 (24) 127 (25) 1.4
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Laboratory measures, %
Abnormal creatinine levels
(> 2 mg/dL)
15.1 21.0 15.4 21.2 20.6 1.5
Thrombocytopenia (< 100 x 10
9
/L) 2.3 7.8 25.3 4.9 6.7 7.7
Anemia*
19.1
44.7
57.1
46.8
43.9
5.8
Abbreviations: yr, years; SD, standard deviation; bpm, beats per minute; SBP, systolic blood pressure.
*Defined as haemoglobin (Hb) < 13 g/dL in men and Hb < 12 g/dL in women.
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Table 4. Patient characteristics according to initial presentation, before and after matching
Before matching After matching
Variable No filter
(n = 20,351)
Filter
(n = 152)
Standardized
difference
(%)
No filter
(n = 134)
Filter
(n = 134)
Standardized
difference
(%)
Deep vein thrombosis
Demographic
Age (yr), mean (SD) 63.7 (17.9) 69.3 (14.8) 34.2 71.9 (14.8) 69.7 (14.3) 15.7
Comorbidities, %
Cancer 21.0 39.5 41.1 29.9 36.6 14.3
Immobilization
24.4
57.2
70.8
60.4
56.7
7.5
Recent or active bleeding 1.5 44.7 119.4 41.0 41.8 1.6
Physical exam
Heart rate (bpm), mean (SD) 81 (15) 85 (17) 23.4 88 (17) 85 (17) 19.3
SBP (mm Hg), mean (SD) 133 (21) 130 (22) 12.4 128 (21) 130 (22) 7.3
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Laboratory measures, %
Abnormal creatinine levels
(> 2 mg/dL)
12.6 25.7 33.8 31.3 26.1 11.5
Thrombocytopenia (< 100 x 10
9
/L)
2.5 9.2 28.8 4.5 8.2 15.2
Anemia*
20.2
56.6
80.
7
54.5
56.0
3.0
Variable No filter
(n = 19,420)
Filter
(n = 219)
Standardized
difference
(%)
No filter
(n = 210)
Filter
(n = 210)
Standardized
difference
(%)
Pulmonary embolism
Demographic, %
Age (yr), mean (SD)
67.9 (16.7)
68.5 (14.3)
4.
3
69.2 (14.8)
68.8 (14.2)
2.7
Comorbidities, %
Cancer 21.0 37.0 35.8 36.2 36.7 1.0
Immobilization 24.1 38.8 81.4 40.0 38.6 2.9
Recent* or active bleeding 1.7 28.8 32.1 28.8 28.8 0
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Physical exam
Heart rate (bpm), mean (SD) 93 (20) 95 (19) 10.8 97 (21) 95 (19) 8.0
SBP (mm Hg), mean (SD) 130 (25) 125 (26) 16.9 125 (27) 126 (26) 8.0
Laboratory measures, %
Abnormal creatinine levels
(> 2 mg/dL)
17.7
17.8
0.3
15.7
17.1
3.8
Thrombocytopenia (< 100 x 10
9
/L)
2.1 6.8 22.9 4.8 5.7 4.0
Anemia* 18.0 36.5 42.5 36.2 36.2 0
Abbreviations: yr, years; SD, standard deviation; bpm, beats per minute; SBP, systolic blood pressure.
*Defined as haemoglobin (Hb) < 13 g/dL in men and Hb < 12 g/dL in women.
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Table 5. Adjusted clinical outcomes
Initial presentation 30-day outcome Filter
No./total no. (%)
No filter
No./total no. (%)
OR
(95% CI)
P value
Any VTE
Death 23/344(6.6%) 35/344(10.2%) 0.63 (0.36-1.12) 0.12
PE-related death 6/344 (1.7%) 17/344 (4.9%) 0.35 (0.15-0.43) 0.03
Major
bleeding
13/344(3.8%)
18/344(5.2%)
0.71 (0.35
-
1.46)
0.35
Recurrent VTE 21/344(6.1%) 2/344(0.6%) 11.12 (2.56-
48.19)
< 0.001
Any DVT
a
Death
Major bleeding
Recurrent VTE
8/134 (6.0%)
4/134(3.0%)
2/134(1.5%)
15/134 (11.2%)
5/134(3.7%)
2/134 (1.5%)
0.53 (0.20
-
1.44)
-b
-b
0.21
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Any PE
Death 15/210 (7.1%) 24/210 (11.4%) 0.60 (0.19-1.21) 0.15
Major bleeding 8/210 (3.8%) 14/210 (6.7%) 0.55 (0.23-1.32) 0.18
Recurrent VTE 17/210 (8.1%) 2/210 (1.0%) 9.16 (2.24-32.48) < 0.001
Abbreviations: OR, odds ratio; CI, confidence interval; VTE, venous thromboembolism; DVT, deep vein thrombosis; PE, pulmonary
embolism.
aAdjusted for variables not achieving 10% standardized difference after matching. Final model included the following covariates: age, cancer,
heart rate, creatinine levels, and thrombocytopenia.
bNot calculated because the number of events precluded adjustment
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APPENDIX
Author contributions
Study concept and design: Muriel, Jiménez, Monreal.
Acquisition of data; analysis and interpretation of data; statistical analysis: Muriel, Jiménez,
Aujesky, Bertoletti, Decousus, Laporte, Mismetti, Yusen, Monreal.
Drafting of the manuscript: Muriel, Jiménez, Aujesky, Bertoletti, Decousus, Laporte, Mismetti,
Yusen, Monreal.
Critical revision of the manuscript for important intellectual content: Muriel, Jiménez, Aujesky,
Bertoletti, Decousus, Laporte, Mismetti, Yusen, Monreal.
The corresponding author, David Jiménez, had full access to all the data in the study and had
final responsibility for the decision to submit for publication.
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Coordinator of the RIETE Registry: Dr. Manuel Monreal (Spain)
RIETE Steering Committee Members: Dr. Hervè Decousus (France)
Dr. Paolo Prandoni (Italy)
Dr. Benjamin Brenner (Israel)
RIETE National Coordinators: Dr. Raquel Barba (Spain)
Dr. Pierpaolo Di Micco (Italy)
Dr. Laurent Bertoletti (France)
Dr. Sebastian Schellong (Germany)
Dr. Manolis Papadakis (Greece)
Dr. Inna Tzoran (Israel)
Dr. Abilio Reis (Portugal)
Dr. Marijan Bosevski (R.Macedonia)
Dr. Henri Bounameaux (Switzerland)
Dr. Radovan Malý (Czech Republic)
RIETE Registry Coordinating Center: S & H Medical Science Service
Members of the RIETE Group
SPAIN: Arcelus JI, Arroyo M, Auguet T, Ballaz A, Barba R, Barrón M, Barrón-Andrés B,
Bascuñana J, Bedate P, Blanco-Molina A, Bueso T, Casado I, del Molino F, del Toro J,
Falgá C, Fernández-Capitán C, Fole D, Gallego P, García-Bragado F, Gavín O, Gómez V,
González J, González-Bachs E, Grau E, Guijarro R, Gutiérrez J, Hernández L,
Hernández-Huerta S, Jara-Palomares L, Jaras MJ, Jiménez D, Lecumberri R, Lobo JL,
López L, López-Jiménez L, López-Sáez JB, Lorente MA, Lorenzo A, Luque JM,
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Madridano O, Maestre A, Marchena PJ, Martín M, Martín-Villasclaras JJ, Monreal M,
Muñoz FJ, Nauffal MD, Nieto JA, Núñez MJ, Ogea JL, Otero R, Pedrajas JM, Pérez G,
Peris ML, Quezada CA, Riera-Mestre A, Rivas A, Rodríguez-Dávila MA, Román P,
Roncero A, Rosa V, Ruiz J, Ruiz-Gamietea A, Ruiz-Giménez N, Sahuquillo JC, Samperiz
A, Sánchez Muñoz-Torrero JF, Soler S, Tiberio G, Tolosa C,Trujillo J, Uresandi F, Valero
B, Valle R, Vela J, Vidal G, Villalobos A, Villalta J, CZECH REPUBLIC: Malý R,
Miklošová M, Hirmerova J, ECUADOR: Parraga S, Salgado E, Sánchez GT, FRANCE :
Bertoletti L, Bura-Riviere A, Farge-Bancel D, Mahe I, Merah A, Quere I, GERMANY:
Schellong S, GREECE: Babalis D, Papadakis M, Tzinieris I IRELAND: Faul J, ISRAEL:
Braester A, Brenner B, Tzoran I, Zeltser D, ITALY: Barillari G, Ciammaichella M, Di
Micco P, Dalla Valle F, Duce R, Maida R, Pasca S, Piovaccari G, Piovella C, Poggio R,
Prandoni P, Quintavalla R, Rocci A, Rota L, Schenone A, Tiraferri E, Tonello D, Tufano
A, Visonà A, Zalunardo B, PORTUGAL: Brinquinho MI, Gonçalves F, Rodrigues AM,
Santos M, Saraiva M, REPUBLIC OF MACEDONIA: Bosevski M, SWITZERLAND: Alatri
A, Aujeski D, Bounameaux H, Calanca L, Mazzolai L.
