Know Patients’ Risk for VTE

Know what the literature says about patients’ risk for VTE

Fluency with the evidence base and best practice for VTE prevention is as an especially important credential for team leaders and the content expert. Command of the literature, guidelines, and performance measures will not only boost your team’s credibility, it is fundamental to your improvement intervention and your performance tracking system. We recommend reading the 7th ACCP Conference on Antithrombotic and Thrombolytic Therapy and details of The Joint Commission and SCIP measures for VTE. We recommend supplementing that consensus statement with the reading list in the Literature Review section of this resource room. When laying out the evidence for VTE prevention you will find at least three central themes, each with important implications for your team.

Theme 1: While the number and type of VTE risk factors appear to influence a patient’s overall VTE risk, there is no validated method to predict a patient’s risk for VTE. 

The 7th ACCP Conference article specifically says: “there is little formal understanding of how the various risk factors interact to determine the position of each patient along a continuous spectrum of thromboembolic risk.”

What this means is that any system for stratifying patients into VTE risk categories may be as good (or as bad) as another. So whatever valuable time and effort you expend – and whatever battles you fight – don’t get hung up on a specific risk stratification system. It is far more important to settle on something that can be widely embraced than to spend resources and political capital on something that you happen to think is perfect.    

The 7th ACCP Conference article offers the following insight into approaches used for VTE risk stratification. The main emphasis is in implementing group-specific prophylaxis.

One approach considers the risk of VTE in each patient, based on their individual predisposing factors and the risk associated with their current illness or procedure. Prophylaxis is then individually prescribed based on the composite risk estimate. Formal risk assessment models for DVT have been proposed to assist with this process.1,67,85–93 Because the approach of individual prophylaxis prescribing, based on formal risk-assessment models, has not been adequately validated and is cumbersome without the use of computer technology, it is unlikely to be used routinely by most clinicians. Furthermore, there is little formal understanding of how the various risk factors interact to determine the position of each patient along a continuous spectrum of thromboembolic risk. One simplification of this process for surgical patients involves assigning them to one of four VTE risk levels based on the type of operation (eg, minor or major), age (eg, < 40 years, 40 to 60 years, and > 60 years), and the presence of additional risk factors (eg, cancer or previous VTE)...Despite its limitations, this classification system, which was derived using prospective study data, provides both an estimate of VTE risk and related prophylaxis recommendations. The second approach involves the implementation of group-specific prophylaxis routinely for all patients who belong to each of the major target groups. We support the latter for several reasons. First, we are unable to confidently identify individual patients who do not require prophylaxis.94 Second, an individualized approach to prophylaxis has not been subjected to rigorous clinical evaluation. Third, individualizing prophylaxis is logistically complex and is likely associated with suboptimal compliance. (Geerts WH, Pineo GF, Heit JA. Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest. 2004 Sep;126(3 Suppl):338S-400S. Review.)

We agree with this second approach. In real terms, we favor constructing simple models that stratify all patients into 3-4 easy to understand groups, as opposed to more complicated point scoring systems. Later in Section 1, when the concept of the VTE protocol is introduced, you may find it helpful to refer back to this passage.