Clinical Review

Decision Making in Venous Thromboembolism


 

References

We also note that several scoring systems (HAS-BLED, HEMORR2HAGES, and ATRIA scores) have been developed to predict those at high risk of bleeding on anticoagulation for atrial fibrillation [78–80].These scores generally include similar clinical risk factors to those in the RIETE and ACCP scoring systems. Several studies have compared the HAS-BLED, HEMORR2HAGES, and ATRIA scores and a systematic review and meta-analysis concluded that the HAS-BLED score is recommended, due to increased sensitivity and ease of application [81].However, as these scores have not been validated for anticoagulation in the setting of VTE, we do not use them in this capacity.

Risk Stratification for Recurrent VTE

When predicting risk of recurrent VTE, clinical risk factors including obesity, male gender, and underlying thrombophilia (including the “high risk” inherited thrombophilias identified above) must taken into consideration. Location of the thrombus must also be considered; it has also been demonstrated that patients with DVT involving the iliofemoral veins are at higher risk of recurrence than those without iliac involvement [82].Other factors that may be useful in risk stratification include D-dimer level and ultrasound to search for residual venous thrombosis.

D-dimer Levels

D-dimer levels are one of the more promising methods for assessing the risk of recurrent VTE after cessation of anticoagulation, especially in the case of idiopathic VTE where indefinite anticoagulation should be considered but may pose either risk of bleeding or significant inconvenience to patients. A normal D-dimer measured 1 month after cessation of anticoagulation offers a high negative predictive value for risk of recurrence [83].A number of studies have demonstrated that patients with elevated D-dimer 1 month after anticoagulation cessation are at increased risk for a recurrent event [84–86].Two predictive models that have been developed incorporate D-dimer testing into decision making [87,88].The DASH predictive model relies on the D-dimer result in addition to age, male sex, and use of hormone therapy as a method of risk stratification for recurrent VTE in patients with a first unprovoked event. Using this scoring system, patients with a score of 0 or 1 had a recurrence rate of 3.1%, those with a score of 2 a recurrence rate of 6.4%, and those with a score of 3 or greater a recurrence rate of 12.3%. The authors postulate that by using this assessment scheme they can avoid lifelong anticoagulation in 51% of patients. The Vienna prediction model uses male sex, location of VTE (proximal DVT and PE are at higher risk), and D-dimer level to predict risk of recurrent VTE. This model has recently been updated to include a “dynamic” component to predict risk of recurrence of VTE from multiple random time points [89].

Overall, D-dimer may be useful for risk stratification. We often employ the method of stopping anticoagulation in patients with unprovoked VTE after 3 months (if the patient has no identifiable clinical risk factors that place them at high risk of recurrence) and testing D-dimer 1 month after cessation of anticoagulation. An elevated D-dimer is a solid reason to restart anticoagulation (potentially on an indefinite basis), while a negative D-dimer provides support for withholding further anticoagulation in the absence of other significant risk factors for recurrence. However, lack of agreement regarding assay cut-points as well as multiple reasons other than VTE for D-dimer elevation may limit widespread use of this method. We generally use a cutpoint of 250 ug/L as “negative,” though at least one study showed that cut-points of 250 ug/L versus 500 ug/L did not change the utility of this method [90].In our practice, risk prediction models are most useful to provide patients with additional information and a visual presentation to support our recommendation. This is particularly true of the Vienna prediction rule, which is available in a printable nomogram which can be distributed to patients and completed together during the clinic visit.

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