Do you still use anticoagulants (blood thinners) for inpatients with a positive COVID-19 (Coronavirus disease 2019) test?

Anticoagulation for COVID-19 Positive Inpatients

Yes, anticoagulant thromboprophylaxis is still recommended for inpatients with a positive COVID-19 test, with prophylactic-intensity anticoagulation being the standard approach for most patients.

Recommendations Based on Patient Status

For Acutely Ill Hospitalized COVID-19 Patients:

• In the absence of contraindications, prophylactic anticoagulation is suggested over no anticoagulation 1
• Low-molecular-weight heparin (LMWH) or fondaparinux is preferred over unfractionated heparin (UFH) 1
• Standard prophylactic dosing is recommended over intermediate or full treatment dosing 1
• However, the most recent ASH guidelines (2025) suggest therapeutic-intensity may be considered over prophylactic-intensity in this population 1

For Critically Ill COVID-19 Patients:

• Anticoagulant thromboprophylaxis is strongly recommended 1
• LMWH is suggested over UFH to limit staff exposure 1
• Standard prophylactic dosing is suggested over intermediate or full treatment dosing 1
• Avoid direct oral anticoagulants (DOACs) due to:
  • Risk of rapid clinical deterioration
  • Potential drug-drug interactions with COVID-19 treatments
  • High incidence of acute kidney injury 1

Medication Selection

Preferred agents (in order):

1. LMWH (first choice for most patients)
2. Fondaparinux (for non-critically ill)
3. UFH (when LMWH is contraindicated or unavailable)

Avoid:

• DOACs for inpatients (high risk of interactions with COVID-19 treatments)
• Antiplatelet agents for VTE prevention 1

Duration of Treatment

• Limit thromboprophylaxis to inpatient stay only 1
• Extended post-discharge thromboprophylaxis is not routinely recommended 1

Special Considerations

• Contraindications: Use mechanical thromboprophylaxis when pharmacological options are contraindicated 1
• Monitoring: No routine ultrasound screening for asymptomatic DVT is recommended 1
• Confirmed VTE: For patients who develop confirmed proximal DVT or PE, therapeutic anticoagulation is recommended for a minimum of three months 1

Pitfalls to Avoid

1. Inappropriate dosing: Using intermediate or therapeutic dosing when not indicated can increase bleeding risk without clear benefit in most patients
2. Overlooking contraindications: Always assess bleeding risk before initiating anticoagulation
3. Using DOACs in critically ill patients: These should be avoided due to potential drug interactions, hemodynamic instability, and renal dysfunction
4. Continuing prophylaxis after discharge: Current evidence does not support routine extended thromboprophylaxis after hospital discharge

The evidence supporting these recommendations is based on expert consensus and observational data, as noted by the American College of Chest Physicians and the American Society of Hematology guidelines. While COVID-19 increases thrombotic risk, the optimal approach balances this risk against bleeding potential.