Recommendation grades (A-C) and levels of evidence (Ia-IV) are defined at the end of the "Major Recommendations" field.
- Vena cava (VC) filters are indicated to prevent pulmonary embolus (PE) in patients with venous thromboembolism (VTE) who have a contraindication to anticoagulation (grade B, level III).
- Anticoagulation should be considered in patients with a VC filter when a temporary contraindication to anticoagulant therapy is no longer present. Insufficient data exists to support a recommendation that all filter recipients should be treated with indefinite anticoagulation regardless of their risk of recurrent thrombosis (grade C, level IV). The decision as to whether or not to introduce anticoagulant therapy should be based on the perceived underlying thrombotic risk of the condition and the likelihood of anticoagulant therapy-related bleeding.
- VC filters are not indicated in unselected patients with VTE who will receive conventional anticoagulant therapy (grade A, level Ib).
- VC filter insertion may be considered in selected patients with PE despite therapeutic anticoagulation. Alternative treatment options, such as long-term high-intensity oral anticoagulant therapy (international normalised ratio [INR] target 3.5) or low molecular weight heparin (LMWH), should be considered prior to VC filter placement, particularly in patients with thrombophilic disorders (e.g., antiphospholipid syndrome) or cancer (grade C, level IV).
- VC filter insertion may be considered in pregnant patients who have contraindications to anticoagulation or develop extensive VTE shortly before delivery (within 2 weeks). Retrievable filters should be considered (grade C, level IV).
- Free-floating thrombus is not an indication for insertion of a VC filter (grade B, level III).
- Thrombolysis is not an indication for filter insertion. If a filter is used a retrievable filter should be used if available (grade C, level IV).
- VC filters should be considered in any pre-operative patient with recent VTE (within 1 month) in whom anticoagulation must be interrupted. Retrievable VC filters should be considered in this situation where a temporary contraindication to anticoagulation exists (grade C, level IV).
- No particular filter appears superior to others. Removable filters should be used, if available, for patients with a short-term contraindication to anticoagulant therapy (e.g., approximately 2 weeks) (grade C, level IV).
Definitions:
Classification of Evidence Levels
Ia Evidence obtained from meta-analysis of randomised controlled trials.
Ib Evidence obtained from at least one randomised controlled trial.
IIa Evidence obtained from at least one well-designed controlled study without randomisation.
IIb Evidence obtained from at least one other type of well-designed quasi-experimental study (a situation in which implementation of an intervention is without the control of the investigators, but an opportunity exists to evaluate its effect).
III Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies and case studies.
IV Evidence obtained from expert committee reports or opinions and/or clinical experiences of respected authorities.
Classification of Grades of Recommendations
Grade A - Requires at least one randomised controlled trial as part of a body of literature of overall good quality and consistency addressing specific recommendation (Evidence levels Ia, Ib).
Grade B - Requires the availability of well conducted clinical studies but no randomised clinical trials on the topic of recommendation (Evidence levels IIa, IIb, III).
Grade C - Requires evidence obtained from expert committee reports or opinions and/or clinical experiences of respected authorities. Indicates an absence of directly applicable clinical studies of good quality (Evidence level IV).
