Venous thromboembolism (VTE) is the third most common cardiovascular diagnosis and includes deep vein thrombosis (DVT), in which a blood clot typically forms in the deep veins of the leg, and pulmonary embolism (PE), a potentially life-threatening event in which a blood clot breaks free and lodges in the arteries of the lung. Approximately half of all thrombotic events are related to a current or recent hospital admission for surgery or acute medical illness. Certain populations are at increased risk for VTE, including medical inpatients, individuals residing in long-term care facilities, individuals with minor injuries, and long-distance travelers.

Recognizing the need for a comprehensive set of guidelines for the treatment of VTE, the American Society of Hematology (ASH) and the McMaster University GRADE Center in Ontario, Canada, initiated a collaboration in 2015 to develop clinical practice guidelines on the diagnosis and treatment of VTE.

“The most important way that these guidelines differ from current guidelines is by their comprehensiveness,” said Adam Cuker, MD, MS, chair of the ASH VTE Guidelines Coordination Panel, clinical director of the Penn Blood Disorders Center, and director of the Penn Comprehensive and Hemophilia Thrombosis Program at the University of Pennsylvania in Philadelphia. “This is meant to be a comprehensive suite of guidelines on virtually all issues related to VTE.”

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For example, the National Institute for Health and Care Excellence (NICE) guidelines concentrate on particular aspects of VTE. “They are focused on risk mitigation strategies for prevention of VTE in hospitalized adult patients,” said Dr Cuker, whereas the ASH guidelines cover prevention, diagnosis, and management in a wide patient population, including sections devoted to managing VTE during pregnancy and in pediatric patients.

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Overall, the guidelines include 10 chapters:

  • Prophylaxis for Medical Patients
  • Diagnosis
  • Anticoagulation Therapy
  • Heparin-Induced Thrombocytopenia (HIT)
  • Pregnancy
  • Pediatrics
  • Treatment
  • Cancer
  • Thrombophilia
  • Prophylaxis in Surgical Patients

“The ASH chapter on prophylaxis is the most similar in scope to the NICE guidelines,” said Dr Cuker. “Six chapters have already been published, and we expect the remaining 4 to be published in 2019.”

He added that the panels for all 10 chapters have finished drafting recommendations, with a final count of 250 guidelines. “That is what makes this effort stand out the most — its scope and comprehensiveness,” noted Dr Cuker.

Prophylaxis for Hospitalized and Nonhospitalized Medical Patients

This chapter in the ASH guidelines identifies methods to prevent VTE in hospitalized and nonhospitalized medical patients and long-distance travelers, all of whom are at a higher risk for developing VTEs. Overall, the panel agreed on 19 recommendations for prophylaxis in these patient populations.1

“This chapter [covered] who should receive intervention and what that intervention should be,” said Mary Cushman, MD, chair of the panel for VTE prevention in medical patients and medical director of the Thrombosis and Hemostasis Program at the University of Vermont in Burlington. “We covered what we know to be the best approaches based on our extensive data and literature review for prevention in these patients while minimizing overtreatment.”

Speaking during a webcast that unveiled the new guidelines, she explained that the panel looked at data from patients admitted to medical wards and intensive care units, as well as individuals who were residents in nursing homes, had experienced minor injuries, and were long distance travelers.

“The first step in this process is to consider their risk of VTE as well as their risk of bleeding complications,” Dr Cushman said.

The key recommendations are:

  • In acutely ill medical patients, pharmacologic VTE prophylaxis is recommended. Low molecular weight heparin (LMWH), unfractionated heparin (UFH), or fondaparinux are suggested, as opposed to not using a parenteral anticoagulant. However, LMWH or fondaparinux is preferred over UFH. These recommendations also apply to patients who have experienced a stroke.
  • In acutely or critically ill medical patients, the panel suggests using pharmacologic VTE prophylaxis over mechanical VTE prophylaxis; in patients who are receiving mechanical VTE prophylaxis, pneumatic compression devices or graduated compression stockings are recommended for VTE prophylaxis.
  • The ASH guideline panel recommends using LMWH over direct oral anticoagulants (DOACs) for VTE prophylaxis in acutely ill hospitalized medical patients. It also recommends inpatient VTE prophylaxis with LMWH only instead of inpatient and extended-duration outpatient VTE prophylaxis with DOACs.
  • In chronically ill medical patients, including patients residing in nursing homes, and in medical outpatients with minor provoking risk factors for VTE, the guideline panel suggests not using VTE prophylaxis at all.
  • In long distance (>4 hours) travelers without risk factors for VTE, the panel suggests not using graduated compression stockings, LMWH, or aspirin for VTE prophylaxis, but for those who are at a substantially increased VTE risk, the use of graduated compression stockings or prophylactic LMWH is suggested.