Key messages

• There might be little or no difference in the occurrence of deep venous thrombosis when an inferior vena cava filter is added in anticoagulated patients.
• It is unclear whether there are differences in the occurrence of pulmonary embolism or mortality by adding an inferior vena cava filter in anticoagulated patients because the certainty of the evidence is very low.

What is the evidence.
See evidence matrix  in Epistemonikos later

We found three systematic reviews [1],[2],[3] including four primary studies answering the question of interest, reported in six references [4],[5],[6],[7],[8],[9]. All of the studies correspond to randomized controlled trials.

What types of patients were included*

All of the trials included patients at high risk for pulmonary embolism [4],[7],[8],[9].

One trial (PREPIC) included patients with documented proximal deep vein thrombosis or pulmonary embolism [4], another trial included patients with documented deep vein thrombosis and cancer [7], another trial (FILTER-PEVI) included patients with symptomatic proximal deep venous thrombosis [8], and the remaining trial included inpatients with symptomatic acute pulmonary embolism with pre-existing deep venous thrombosis presenting a high risk of recurrence [9].

What types of interventions were included*

All of the trials evaluated the addition of an inferior vena cava filter to anticoagulant treatment for the prevention of pulmonary embolism.

Two trials used a permanent filter; one used Vena Tech LGM, B. Braun; Titanium Greenfield, Boston Scientific; Cardial, Bard; Bird's Nest, Cook Group [4], and the other trial used Vena Tech Vena TMLP, B. Braun [7]. One trial used a removable vena cava filter (ALN filter, ALN Implants Chirurgicaux) [9]. One trial used several filters (Celect, Tulip [Cook Medical, Bloomington, IN], Optease [Cordis,Miami, FL]; Eclipse [Bard, Tempe, AZ]) ** [8].

All trials compared against anticoagulant treatment; one trial used low molecular weight heparin (enoxaparin), unfractionated heparin or vitamin K antagonists [4]; one trial used fondaparinux [7]; another trial used tinzaparin, enoxaparin, fondaparinux, unfractionated heparin or vitamin K antagonists; the remaining trial used enoxaparin or unfractionated heparin in those with renal insufficiency, followed by warfarin ** [8].

What types of outcomes
were measured

The different systematic reviews grouped the outcomes as follows:

• New pulmonary embolism
• Recurrent pulmonary embolism
• New deep venous thrombosis
• Recurrent deep venous thrombosis
• Mortality (all-cause)
• Major bleeding
• Thrombosis distal to the inferior vena cava filter
• Complications related to the inferior vena cava filter

To whom this evidence does and does not apply

• The evidence presented in this summary applies to patients at high risk of developing pulmonary embolism with demonstrated thromboembolic disease.
• It does not apply to patients who have a formal contraindication for anticoagulation, which is one of the most common situations in which the use of vena cava filters is proposed in the medical practice.

• The outcomes included in the summary of findings table are those considered critical for decision-making by the authors of this summary. These generally coincide with those evaluated in the systematic reviews identified and in the main clinical guidelines.
• It should be noted that in many of these trials, pulmonary embolism and deep venous thrombosis were screened even in the absence of symptoms, which could overestimate the incidence of events and show differences of arguable clinical value.

• Given the uncertainty derived from the available evidence, it is not possible to make an adequate balance on the risk/benefit of this intervention.

• Adding anf inferior vena cava filter to anticoagulation leads to increased costs.
• It is not possible to make an adequate balance between costs and benefits due to the existing uncertainty.

• With the evidence presented in this summary most patients and clinicians should lean against the use of the intervention.

Differences between this summary and other sources

• The conclusions of this summary are consistent with those of two reviews identified [2],[3]. Another review [1] concluded that there is a decrease in the risk of pulmonary embolism with the addition of an inferior vena cava filter.
• Our summary agrees with the conclusions of the American College of Chest Physicians 2016 clinical guideline [10] that recommends against the use of an inferior vena cava filter in patients with acute events of deep venous thrombosis or pulmonary embolism who can receive anticoagulant treatment.

• The probability that the conclusions of this summary would change in the future is high, due to the existing uncertainty.
• However, we did not identify any ongoing trial evaluating this question in the International Clinical Trials Registry Platform of the World Health Organization.