. 2021 Oct 14;5(20):3951–3959. doi: 10.1182/bloodadvances.2021005493

Table 1.

Recommendations

Recommendation	Remarks
Recommendation 1a. The ASH guideline panel suggests using prophylactic-intensity over intermediate-intensity anticoagulation in patients with COVID-19–related critical illness who do not have suspected or confirmed VTE (conditional recommendation based on low certainty in the evidence about effects ⨁⨁◯◯).	• The ASH guideline panel plans to continue to update this recommendation when the full results of other trials become available. Clinicians should weigh the potential benefits and harms based on the most up-to-date evidence in caring for their patients. • A now-expired recommendation published on 27 October 2020 compared therapeutic-intensity or intermediate-intensity with prophylactic-intensity anticoagulation in patients with COVID-19–related critical illness. With the emergence of new evidence, this recommendation has now been split into 2 recommendations: a recommendation comparing intermediate-intensity vs prophylactic-intensity anticoagulation (Recommendation 1a) and a separate recommendation comparing therapeutic-intensity vs prophylactic-intensity anticoagulation (Recommendation 1b), whereby the latter remains unchanged for now, but, as with other recommendations in this guideline, is subject to review and revision as new evidence becomes available that meets prespecified criteria for updating. • Patients with COVID-19–related critical illness are defined as those suffering from an immediately life-threatening condition who would typically be admitted to an ICU. Examples include patients requiring hemodynamic support, ventilator support, and renal replacement therapy. • An individualized assessment of the patient’s risk of thrombosis and bleeding is important when deciding on anticoagulation intensity. Risk assessment models to estimate thrombotic and bleeding risk in hospitalized patients are available, but they have not been prospectively validated in patients with COVID-19. • At present, there is no direct high-certainty evidence comparing different types of anticoagulants. The selection of a specific agent (eg, LMWH, UFH) may be based on availability, resources required, familiarity, and the aim of minimizing the use of personal protective equipment or staff exposure to COVID-19–infected patients as well as patient-specific factors (eg, renal function, history of heparin-induced thrombocytopenia, concerns about gastrointestinal tract absorption). • This recommendation does not apply to patients who require anticoagulation to prevent thrombosis of extracorporeal circuits such as those on extracorporeal membrane oxygenation or continuous renal replacement therapy.

Recommendation

Remarks

Recommendation 1a. The ASH guideline panel suggests using prophylactic-intensity over intermediate-intensity anticoagulation in patients with COVID-19–related critical illness who do not have suspected or confirmed VTE (conditional recommendation based on low certainty in the evidence about effects ⨁⨁◯◯).

• The ASH guideline panel plans to continue to update this recommendation when the full results of other trials become available. Clinicians should weigh the potential benefits and harms based on the most up-to-date evidence in caring for their patients.
• A now-expired recommendation published on 27 October 2020 compared therapeutic-intensity or intermediate-intensity with prophylactic-intensity anticoagulation in patients with COVID-19–related critical illness. With the emergence of new evidence, this recommendation has now been split into 2 recommendations: a recommendation comparing intermediate-intensity vs prophylactic-intensity anticoagulation (Recommendation 1a) and a separate recommendation comparing therapeutic-intensity vs prophylactic-intensity anticoagulation (Recommendation 1b), whereby the latter remains unchanged for now, but, as with other recommendations in this guideline, is subject to review and revision as new evidence becomes available that meets prespecified criteria for updating.
• Patients with COVID-19–related critical illness are defined as those suffering from an immediately life-threatening condition who would typically be admitted to an ICU. Examples include patients requiring hemodynamic support, ventilator support, and renal replacement therapy.
• An individualized assessment of the patient’s risk of thrombosis and bleeding is important when deciding on anticoagulation intensity. Risk assessment models to estimate thrombotic and bleeding risk in hospitalized patients are available, but they have not been prospectively validated in patients with COVID-19.
• At present, there is no direct high-certainty evidence comparing different types of anticoagulants. The selection of a specific agent (eg, LMWH, UFH) may be based on availability, resources required, familiarity, and the aim of minimizing the use of personal protective equipment or staff exposure to COVID-19–infected patients as well as patient-specific factors (eg, renal function, history of heparin-induced thrombocytopenia, concerns about gastrointestinal tract absorption).
• This recommendation does not apply to patients who require anticoagulation to prevent thrombosis of extracorporeal circuits such as those on extracorporeal membrane oxygenation or continuous renal replacement therapy.