Should We Not Be Using IVC Filters in Trauma Patients?

Background: Trauma patients can be a rather difficult patient population to treat with multiple ongoing issues.  There is always a balance of hemorrhage control vs prophylaxis for venous thromboembolism (VTE), as both can cause increased morbidity and mortality.  One method to balance this challenging issue is retrievable inferior vena cava (IVC) filters, which at face value sound like a nice solution (Prevent VTE while avoiding worsening hemorrhage).  The main issue with IVC filters is there is limited high quality data to support the use of these devices and IVC filters are not without their own long-term complications as well. Finally, there are also conflicting recommendations depending on which guidelines you choose to read [3][4][5].

Guideline Recommendations for Vena Cava Filters

EAST Trauma Guidelines [4]

• Level III: Insertion of a “prophylactic” vena cava filter should be considered in very-high-risk trauma patients:
  • Who cannot receive anticoagulation because of in- creased bleeding risk, AND
  • Have an injury patterns rendering them immobilized for a prolonged period of time, including the following:
    • Severe closed head injury (GCS score 􏰁 8).
    • Incomplete spinal cord injury with paraplegia or quadriplegia.
    • Complex pelvic fractures with associated long bone fractures.
    • Multiple long bone fractures.

American College of Chest Physicians [5]

• For major trauma patients, we suggest that an IVC filter should not be used for primary VTE prevention (Grade 2C)

What They Did:

• Multicenter, randomized, controlled trial in Australia
• 240 severely injured patients (ISS >15) with contraindication to anticoagulant agents randomized to IVC filter placed within 1^st 72hrs after admission vs no filter placed
• All patients underwent ultrasonography of the legs at 2 weeks
• Patients also had CTPA done when prespecified criteria were met:
  • SBP <90mmHg for >30 min OR
  • Unexplained chest pain OR
  • Hypoxia requiring ≥6LPM of oxygen or 50% O2 to maintain arterial O2 saturation >94%

Outcomes:

• Primary:
  • Composite of symptomatic PE or death from any cause at 90 days after enrollment
  • Cost effectiveness of vena cava filters in severely injured patients (results of this outcome were not reported in this publication)
• Secondary:
  • Symptomatic PE between day 8 and 90 in a subgroup of patients who survived at least 7 days and did not receive prophylactic anticoagulation within 7 days after injury
  • Complications related to vena cava filters
  • Death at 90 days
  • Major and nonmajor bleeding at 90 days
  • DVT at 90d (not prespecified in the original protocol)

Inclusion:

• ≥18 years of age
• Estimated ISS >15
• Contraindication to receipt of prophylactic anticoagulation within 72hrs after admission for the injury 

Exclusion:

• Imminent death
• Confirmed PE on admission to the trial center
• Systemic anticoagulant treatment before injury
• Pregnancy
• Unavailability of an interventional radiologist to insert the filter within 72 hours after admission

Results:

• 240 severely injured patients (ISS >15) with contraindication to anticoagulant agents
  • Median age of 39 years (Range 27 – 57 years)
  • Median ISS = 27 (Range 22 – 34)
  • 138 pts (57.5%) had traumatic intracranial hematoma or contusions (74 in IVC group and 64 in control group)
  • Of 122 pts assigned to IVC filter group, 89% had filter inserted within 24hrs after enrollment (median 15.6hrs)
• Composite of symptomatic PE or death from any cause at 90 days (Primary Outcome):
  • Early IVC filter: 13.9%
  • No IVC filter: 14.4%
  • HR 0.99; 95% CI 0.51 – 1.94; p = 0.98
• Patients who survived 7 days and did not receive prophylactic anticoagulation within 7 days after injury:
  • IVC Filter Group: 0/46 PEs (0%)
  • No IVC Filter Group: 5/34 PEs (14.7%)
    • All occurred between day 9 and day 19 after the injury
  • RR 0; 95% CI 0.00 – 0.55
• No difference in death from any cause at 90 days, incidence of major and non-major bleeding at 90 days, DVT, or transfusion requirements
• Complications associated with IVC filters:
  • Entrapped thrombus found in filter in 6/122 pts (4.9%; 95% CI 2.2 – 9.8)
  • Need for surgical removal of IVC filter in 1/108 pts (0.9%; 95% CI 0.1 – 4.5)
  • Filter not removed because of technical reasons or because of loss to follow up in 34/108 pts (31.5%)

Strengths:

• Baseline characteristics of patients were well balanced between groups
• No financial or non-monetary support was received from any companies that manufacture vena cava filters or from commercial entities
• Independent data and safety monitoring committee provided safety oversight
• Independent statistical company maintained the web-response randomization portal, held the clinical database, and conducted all analyses independent of the investigators
• PEs were confirmed by an independent consultant radiologist or by postmortem examination

Limitations:

• Although appropriate for this study, patients and clinicians were aware of group assignment, which means the study was unblinded and could result in detection bias
• Although billed as a multicenter, this trial enrolled most patients at a single center, which is a potential for bias
• Use of a composite outcome can lead to a skewed result.Was it really the PE that was the primary cause of death or incidentally, was a PE there and patients died from another cause, which is now included in the primary outcome
• 1714 patients screened for eligibility, and 1006 excluded due to having received or planned to receive anticoagulants within 72hrs after admission limiting the size of the study
• The study was underpowered to detect a lower incidence of symptomatic pulmonary embolism or death in the IVC filter group than in the control group
• Secondary outcomes required patient had to survive to 7 days to qualify for inclusion which introduces survivor bias (i.e. less sick and conceivably at a lower risk for PE than patients who died earlier)

Discussion:             

• All filters were removed as soon as prophylactic anticoagulation was resumed or before 90 days, unless there was a strong indication to leave the filter longer than this prespecified period
• Most patients received intermittent pneumatic compression to uninjured legs, which in my mind makes this a vena cava filter vs intermittent pneumatic compression device trial
• Meta-analysis of 11 studies (6 RCTs and 5 observational trials) looking at use of IVC filters [2]:
  • Quality of evidence for RCTs was low to moderate
  • Lower risk for subsequent PE: OR 0.51; 95% CI 0.33 – 0.75
  • Increased risk for DVT: OR 1.70; 95% CI 1.17 – 2.48
  • No difference in PE-related mortality: OR 0.51; 95% CI 0.25 – 1.05
  • No change in all-cause mortality: OR 0.91; 95% CI 0.70 – 1.19
• Anticoagulation was initiated within 7 days after severe injury in 67% of patients enrolled in this trial.This subset of patients would most likely not benefit from IVC filter placement in the first place
• In patients who did not receive anticoagulation within 7 days, 69% had intracranial hematomas or contusions.
• The absence of increased DVTs in this study with IVC filters may be a result of use of intermittent pneumatic compression devices, initiation of prophylactic anticoagulation, and the removal of IVC filters as early as possible

Author Conclusion: “Early prophylactic placement of a vena cava filter after major trauma did not result in a lower incidence of symptomatic pulmonary embolism or death at 90 days than no placement of a filter.”

Clinical Take Home Point: Although the use of IVC filters makes sense in theory, the evidence thus far for their use has not shown improvement in PE-related mortality or all-cause mortality. This small underpowered study should therefore not change practice of not using IVC filters in trauma patients. It appears the use of intermittent compression devices plus starting prophylactic anticoagulation when safe is just as good at preventing PEs and death without the risk of complications.

References:

1. Ho KM et al. A Multicenter Trial of Vena Cava Filters in Severely Injured Patients. NEJM 2019. PMID: 31259488
2. Bikdeli B et al. Inferior Vena Cava Filters to Prevent Pulmonary Embolism: Systematic Review and Meta-Analysis. JACC 2017. PMID: 28935036
3. Kaufman JA et al. Guidelines for the Use of Retrievable and Convertible Vena Cava Filters: Report From the Society of Interventional Radiology Multidisciplinary Consensus Conference. J Vasc Interv Radiol 2006. PMID: 16567669
4. Rogers FB et al. Practice Management Guidelines for the Prevention of Venous Thromboembolism in Trauma Patients: The EAST Practice Management Guidelines Work Group. J Traum 2002. PMID: 12131409
5. Guyatt GH et al. Executive Summary: Antithrombotic Therapy and Prevention of Thrombosis, 9^thed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012. PMID: 22315257

For More Thoughts on This Topic Checkout:

• Emlyns: Clot’s the Problem? Vena Cava Filters in Trauma Patients
• The Bottom Line: IVC Filters

Post Peer Reviewed By: Zaf Qassim (Twitter: @emeddoc)