Thromboprophylaxis in Patients with COVID-19: Systematic Review of National and International Clinical Guidance Reports

Background: Venous Thromboembolism (VTE) is common among patients with severe Coronavirus Disease 2019 (COVID-19). Anticoagulation in hospitalized COVID-19 patients has been associated with survival benefit; however, the optimal thromboprophylaxis strategy has not yet been defined. Objective: To identify published guidance reports by national and international societies regarding thromboprophylaxis strategies in COVID-19 patients in different settings (outpatients, hospitalized, post-discharge). Methods: A systematic review of the literature (Pubmed/EMBASE) was conducted independently by two investigators. Results: Among 1942 initially identified articles, 33 guidance documents were included: 20 published by national and 13 by international societies. These documents provide recommendations mainly for hospitalized (97% of reports) and post-discharge (75%) COVID-19 patients, and less so for outpatients (34%). Thrombotic and bleeding risk stratification prior to any treatment decision is the cornerstone of all suggested thromboprophylaxis strategies; 81% of the documents recommend thromboprophylaxis for all hospitalized patients with a prophylactic dosage of low molecular weight heparin irrespective of VTE risk. Intermediate or therapeutic dose intensity is recommended in high VTE risk patients by 56% and 28% of documents, respectively. Mechanical thromboprophylaxis is suggested in case of high bleeding risk or contraindication to pharmacological thromboprophylaxis (59% of documents). Extended pharmacological thromboprophylaxis is recommended for patients with high VTE risk after hospital discharge (63% of documents). For non-hospitalized outpatients, 28% of documents recommend pharmacological thromboprophylaxis for high VTE risk. Conclusion: The current guidance identifies thromboprophylaxis in COVID-19 patients, especially during hospitalization, as of major importance for the prevention of VTE. Recommendations are derived from limited evidence from observational studies.