A Clearinghouse for Information about Blood Clots (DVT/)PE) and Clotting Disorders (thrombophilia) provided as a public service by the University of North Carolina Blood Research Center

For Health Care Professionals: Preventing Thrombosis in COVID-19 –Anticoagulation Algorithm

Stephan Moll, MD writes (last updated: Sept 9th, 2020)…

Background:  Hospitalized patients with COVID-19 are at increased risk for thrombosis – DVT, PE, and may be pulmonary micro-vascular thrombosis that possibly contributes to respiratory failure; arterial events appear to occur less commonly. Scientific/clinical data on prevalence of thrombosis, best prevention, and optimal therapy are limited. Published data suggest that:

  • PE is common, occurring in up to 27 % of hospitalized Intensive care unit patients [1-3].
  • PE and DVT frequently occur in spite of standard-dose anticoagulation [1,3]
  • Anticoagulation in severely sick patients may lead to decreased mortality [4].
  • Microvascular thrombosis in the lung occurs and may be extensive; it can be associated with hemorrhage [5].
  • Major bleeding is observed less frequently than thrombosis [3]
  • The risk for developing a DVT or PE in the 6 weeks after hospital discharge is low, recently reported as being only 0.48% [6].

Anticoagulation Guidance Documents: Some national expert anticoagulation guidance documents exist, such as from the NIH (last updated May 2, 2020) [7], the American Society of Hematology (last reviewed Jul 20, 2020) [8], and the International Society on Thrombosis and Haemostasis (last updated May 2020) [9].

Treatment Algorithm: Our institution (University of North Carolina at Chapel Hill) developed an anticoagulation algorithm, updated Sept 9th, 2020 (link here), in which COVID-19 patients to use anticoagulants and at what dose-intensities. The algorithm was created through discussions between UNC hematologists, intensivists, pulmonologists, and hospitalists and consideration of published data and guidance documents. It is neither overly aggressive, nor overly passive; it’s an intermediate anticoagulant approach.

Underpinnings of our algorithm are as follows:

  • All hospitalized COVID-19 patients need DVT/PE prophylaxis with anticoagulation (unless there are clear bleeding contraindications); however, best drug and dosage are not established.
  • Thrombosis appears to be a bigger problem in COVID-19 patients than bleeding.
  • However, we are also concerned about provoking bleeding by giving anticoagulation too aggressively, particularly when a patient is elderly, has thrombocytopenia (most concerning if platelet count < 50k /μL, coagulopathy with progressive disseminated intravascular coagulation (DIC) leading to decreased coagulation factor levels, renal dysfunction, liver impairment, multi-organ failure, h/o bleeding or active bleeding sites. Bleeding is almost always multi-factorial; therefore, a clinician is to consider ALL bleeding risk factors when making decisions on giving anticoagulation and choosing a dose-intensity.
  • Current scientific uncertainties and controversies pertain to (a) the prevalence of DVT/PE in this population; (b) the failure rate of traditional anticoagulation prophylaxis with respect to recurrent DVT/PE; (c) whether microvascular thrombosis plays a role in the respiratory failure seen in COVID-19; and most importantly: (d) whether anticoagulation (no matter at what dose) prevents or improves thrombosis. Thus, none of the recommendations for empiric higher-doses of anticoagulation are strong recommendations.
  • Patients still need to be evaluated individually with respect to (a) possible etiology of their respiratory and other organ failure, (b) bleeding risk, (c) suitability for anticoagulation.

References

  1. Klok FA et. Incidence of thrombotic complications in critically ill ICU patients with COVID-19. Thromb Res. 2020 Jul;191:145-147 (link here).
  2. Cui S et al. Prevalence of venous thromboembolism in patients with severe novel coronavirus pneumonia. J Thromb Haemost 2020 Jun;18(6):1421-1424 (link here).
  3. Helms J et al. High risk of thrombosis in patients in severe SARS-CoV-2 infection: a multicenter prospective cohort study. Intensive Care Med 2020 Jun;46(6):1089-1098 (link here).
  4. Tang N et al. Anticoagulant treatment is associated with decreased mortality in severe coronavirus disease 2019 patients with coagulopathy. J Thromb Haemost. 2020 May;18(5):1094-1099 (link here).
  5. Fox SE et al. Pulmonary and cardiac pathology in African American patients with COVID-19: an autopsy series from New Orleans. Lancet Respir Med 2020 Jul;8(7):681-686 (link here).
  6. Roberts LN et al. Post-discharge venous thromboembolism following hospital admission with COVID-19. Blood. 2020 Aug 3. Online ahead of print. (link here).
  7. NIH guidance document: Antithrombotic Therapy in Patients with COVID-19 (created May 12, 2020) (link here).
  8. Am Soc Hematology guidance document: COVID-19 and VTE/Anticoagulation: Frequently Asked Questions (last reviewed Jul 20, 2020) (link here).
  9. Spyropoulos AC et al. Scientific and Standardization Committee communication: Clinical guidance on the diagnosis, prevention, and treatment of venous thromboembolism in hospitalized patients with COVID-19. J Thromb Haemost 2020 Aug;18(8):1859-1865 (link here).
  10. Spyropoulos AC et al. Modified IMPROVE VTE Risk Score and Elevated D-Dimer Identify a High Venous Thromboembolism Risk in Acutely Ill Medical Population for Extended Thromboprophylaxis. TH Open. 2020 Mar 13;4(1):e59-e65 (link here).

Stephan Moll

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