Dr. Daniel Rochester

Inpatient VTE prophylaxis

Venous thromboembolism disease [VTE] (ie, pulmonary embolism and deep venous thrombosis) can significantly increase patients hospital stay and put them at risk for worse outcomes. However, preventing VTE does not come without its own risks. In this post we will discuss VTE prophylaxis in hospitalized adults, specifically the different modalities available, and when to use each one. This will focus specifically on patients admitted for medical reasons, as patients admitted for surgical reasons have additional considerations and different guidelines.

To start we need to assess whether a patient should receive VTE prophylaxis. There are several scoring systems that have been developed and studied, but the two that are mentioned in both the guidelines for prevention of VTE by the American College of Chest Physicians (CHEST) and the American Society of Hematology (ASH) are Padua and IMPROVE. (¹, ²)

Padua (²)

Active cancer (+3)
Previous VTE (+3)
Reduced mobility (+3)
Already known thrombophilic condition (+3)
Recent (≤ 1 month) trauma or surgery (+2)
Age ≥ 70 years (+1)
Heart and/or respiratory failure (+1)
Acute MI and/or ischemic stroke (+1)
Acute infection and/or rheumatologic disorder (+1)
Obesity (BMI ≥ 30) (+1)
Ongoing hormonal therapy (+1)

A Padua score of <4 is a low-risk score, and a score ≥ 4 is a high-risk score.

IMPROVE Risk Score for Venous Thromboembolism (³)

Previous VTE (+3)
Known thrombophilia (+2)
Current lower-limb paralysis (+2)
Current cancer (+2)
Immobilized ≥ 7 days (+1)
ICU/CCU stay (+1)
Age > 60 years (+1)

The IMPROVE score calculates an estimated 3-month risk of VTE, from 0.4% with 0 points, to >7.2% with >10 points.

In addition, we need to consider a patient’s bleeding risk, as medications used to prevent VTE will inherently increase the bleeding risk. The IMPROVE bleeding risk score is used in both the CHEST and ASH VTE prophylaxis guidelines to help clinicians determine the risk of using pharmacologic VTE prophylaxis in their patients.

IMPROVE Bleeding Risk Score (⁴)

Age <40 (0), 40-84 (+1.5), ≥ 85 (+3.5)
Gender: Female (0), Male (+1)
Renal function (GFR): ≥ 60 (0), 30-59 (+2), <30 (+2.5)
Current cancer (+2)
Rheumatic disease (+2)
Central venous catheter (+2)
ICU/CCU admission (+2.5)
Evidence of hepatic failure (INR >1.5) (+2.5)
Platelet count ≥ 50 (0), <50 (+4)
Bleeding in 3 months before admission (+4)
Active gastroduodenal ulcer (+4.5)

A score of <7 means the patient is at no increased risk of bleeding. A score of ≥ 7 means the patient is at an increased risk of bleeding.

Before we discuss if a patient should or should not receive VTE prophylaxis, we need to first discuss the two main groups of VTE prophylaxis, mechanical and pharmacologic prophylaxis. Mechanical prophylaxis consists of intermittent pneumatic compression (IPC) and graded compression stockings. These methods work by using compression of the legs to enhance blood flow, decreasing venous stasis.

The two main options for pharmacologic VTE prophylaxis include low molecular weight heparin (LMWH) and low-dose unfractionated heparin. There are a few factors to keep in mind when choosing between these two options, including kidney function and obesity. The usual dose for LMWH is 40mg once daily, and the usual dose for unfractionated heparin is 5000 unites every 8 to 12 hours (CHEST guidelines note that there has been to RCT comparing Q8 hour dosing to Q12 hour dosing, and that it would be acceptable to choose either Q8 or Q12 hour dosing). If a patient has kidney disease the dose of LMWH may need to be reduced. Guidelines recommend that if a patient has a baseline CrCl <30, that the dose of LMWH should be reduced to 30mg once daily. (¹) However, if a patient has a CrCl ≥ 30, but it drops to less than 30 during the hospital stay, LMWH should be switched out for unfractionated heparin as there is no need to dose-adjust for renal function with unfractionated heparin. Obesity is another consideration when it comes to pharmacologic prophylaxis dosing. CHEST guidelines don’t have a recommendation for LMWH dosing, but instead suggest switching those patients to unfractionated heparin and increasing the dose to 7500 units every 8 to 12 hours.

Now we need to decide if a patient needs VTE prophylaxis. Based on their Padua score, you can classify a patient as either low risk for VTE (score <4) or high risk for VTE (score ≥ 4). The IMPROVE score must be considered to determine the risk of VTE. CHEST and ASH guidelines recommend that patients who are at an increased risk for VTE should receive pharmacologic VTE prophylaxis. (¹, ²) The guidelines also state that if a patient who are at low risk for VTE should not receive VTE prophylaxis. But what about bleeding risk? The CHEST and ASH guidelines state that if a patient is as increased risk for bleeding (see IMPROVE bleeding risk score), that mechanical VTE prophylaxis should be used instead of pharmacologic VTE prophylaxis. (¹, ², ⁵)

How long should we anticoagulate?

Both the ASH and CHEST guidelines state that patients who receive VTE prophylaxis should only receive it while hospitalized, and that there is no need to extend VTE prophylaxis after discharge from the hospital. This will not significantly increase the risk of VTE and will reduce the patient’s risk of bleeding. (¹,²)

What about DOACs?

Currently, rivaroxaban is approved for use in the U.S. as VTE prophylaxis for acutely ill hospitalized patients. However, the approval is for 31-39 days of prophylaxis extending into the hospital discharge period. (¹, ⁶) ASH guidelines recommend using LMWH over rivaroxaban, citing increased harm from using rivaroxaban for VTE prophylaxis. The recommendation was based on systemic reviews that showed increased bleeding risk with DOACs compared with minimal effects on mortality. However, the guidelines do note that future research is needed to evaluate lower-dose DOAC and shorter duration DOAC regimens.

Summary:

Determining whether to use VTE prophylaxis starts with determining the patient’s risk for VTE based on their Padua and IMPROVE VTE risk scores. If a patient is low risk, there is no need for VTE prophylaxis. If a patient is at an increased risk for VTE, then prophylaxis should be used. Guidelines recommend pharmacologic over mechanical prophylaxis for patients not at an increased risk for bleeding. For patients at an increased risk for bleeding, the guidelines recommend mechanical VTE prophylaxis over pharmacologic or no VTE prophylaxis. It’s important to keep in mind the patient’s kidney function and weight when deciding between LMWH and unfractionated heparin and the dosing of these medications. In regards to DOACs, the ASH guidelines recommend using LMWH over DOACs for VTE prophylaxis, although it is necessary to keep an eye out as new data may change this recommendation in the future.

Daniel Rochester
**, D.O.**

*University of Louisville | UL · Department of Medicine* | *Internal Medicine Residency Program*
Dr. Daniel Rochester is a Third Year member of the Internal Medicine Residency Program at the University of Louisville. Learn more here.

References:

Kahn, S. R., Lim, W., Dunn, A. S., Cushman, M., Dentali, F., Akl, E. A., Cook, D. J., Balekian, A. A., Klein, R. C., Le, H., Schulman, S., & Murad, M. H. (2012). Prevention of VTE in nonsurgical patients. Chest, 141(2). https://doi.org/10.1378/chest.11-2296
Holger J. Schünemann, Mary Cushman, Allison E. Burnett, Susan R. Kahn, Jan Beyer-Westendorf, Frederick A. Spencer, Suely M. Rezende, Neil A. Zakai, Kenneth A. Bauer, Francesco Dentali, Jill Lansing, Sara Balduzzi, Andrea Darzi, Gian Paolo Morgano, Ignacio Neumann, Robby Nieuwlaat, Juan J. Yepes-Nuñez, Yuan Zhang, Wojtek Wiercioch; American Society of Hematology 2018 guidelines for management of venous thromboembolism: prophylaxis for hospitalized and nonhospitalized medical patients. Blood Adv 2018; 2 (22): 3198–3225. doi: https://doi.org/10.1182/bloodadvances.2018022954
Barbar S, Noventa F, Rossetto V, Ferrari A, Brandolin B, Perlati M, De Bon E, Tormene D, Pagnan A, Prandoni P. A risk assessment model for the identification of hospitalized medical patients at risk for venous thromboembolism: the Padua Prediction Score. J Thromb Haemost. 2010 Nov;8(11):2450-7. doi: 10.1111/j.1538-7836.2010.04044.x.
Spyropoulos AC, Anderson FA, FitzGerald G, et al. Predictive and associative models to identify hospitalized medical patients at risk for VTE. Chest. 2011;140(3):706-714.
Decousus H, Tapson VF, Bergmann JF, et al. Factors at admission associated with bleeding risk in medical patients: findings from the IMPROVE investigators. Chest. 2011;139(1):69-79.
Cohen AT, Spiro TE, Büller HR, et al; MAGELLAN Investigators. Rivaroxaban for thromboprophylaxis in acutely ill medical patients. N Engl J Med. 2013;368(6):513-523. doi:10.1056/NEJMoa1111096 [PubMed 23388003]

Inpatient VTE Prophylaxis