Thrombosis & Covid-19 - Individual Risk Assessment & Prophylaxis Protocol

Prof. Joseph Caprini, Emeritus at the NorthShore University Health System in Evanston, Illinois and a senior clinician-educator at the University of Chicago Pritzker School of Medicine, believes that individual risk assessment of thrombosis in Covid-19 patients is a fundamental part of analyzing the pandemic! As the number and power of risk factors increase in the Caprini Score, the incidence of thrombosis increases, resulting in a score that has been validated in 5 million patients. There is a non-linear increase in clinical venous thromboembolism incidence as the score increases! But capturing the 40 elements in the Caprini Score is a time-consuming process! However, it can be facilitated by having the patient complete a preliminary form in advance of elective surgery with the help of family members. That is why physicians should review the initial documents filled by the patients and their families. However, is there really a connection between Thrombosis and Covid-19?

Joseph Caprini

Is there a connection between Covid-19 and Thrombosis?

Yes, as some of the clinical presentations of Covid-19 include the following:

  1. Deep Vein Thrombosis (DVT)
  2. Pulmonary emboli
  3. Arterial thrombosis
  4. Stroke

But what makes individual risk assessment of thrombosis in Covid-19 patients so important?

Why is an individual risk assessment of thrombosis in Covid-19 patients crucial?

Careful risk assessment is required due to the increased incidence of arterial thrombosis, DVT, PE, stroke, and fatal thrombotic events.  

Two significant risk factors associated with venous thromboembolism are major surgeries and immobility.

1) Why is major surgery a risk factor for thrombosis?

Anaesthesia is the main reason major surgery is a risk factor for thrombosis, as its effects replicate that of Virchow’s Triad.

The effects of Anaesthesia include the following:

  • Venous stasis due to calf muscle paralysis. 
  • Venous overdistension produces endothelial cracks.
  • Hypercoagulability occurs secondary to surgical stress, retained metabolites and underlying pathology.

The longer the patient is kept under anaesthesia, the more intensified these effects become.

To minimize those damaging effects of anaesthesia, performing Intermittent pneumatic compression during surgery is a must!

2) Why is immobility a well-known risk factor for venous thromboembolism?

Prof. Caprini’s definition of immobility includes those who cannot walk 30 feet at one time.

The rate of VTE in non-ambulatory medical patients without prophylaxis was 19.7% compared to 10.6% in those who can walk 30 feet, making immobility a risk factor for venous thromboembolism.

Are abnormal coagulation parameters associated with poor prognosis of patients with novel Coronavirus pneumonia?

Yes, abnormal coagulation parameters are indeed associated with poor prognosis in patients with Covid-19 pneumonia.

Two that play a significant role in this are Factor 11 and Factor 12:

  1. Abnormal coagulation parameter no.1: Factor 11

Inhibition of factor 11 minimizes the activation of the extrinsic clotting cascade. 

Osocimab is a human monoclonal IG G1 antibody that inhibits factor 11 from activating the clotting cascade, which may be beneficial to add to the COVID-19 therapy cocktail. 

  1. Abnormal coagulation parameter no.2: Factor 12

Factor 12 inhibition may offer a novel and promising therapeutic approach to antagonize overwhelming inflammatory responses in ARDS lungs without intervening with vital hemostasis.  

Did you know that patients who do not survive ARDS have a higher level of circulating factor 12?

What are some effective prophylaxis methods for hospitalized Covid-19 patients?

Mechanical methods of prophylaxis are very crucial to use on hospitalized Covid-19 patients. They include the following:

  • Critical component of care for all COVID-19 hospitalized patients, especially those in ICU and on ventilators.
  • IPC is mandatory during surgical procedures.
  • Most data show enhanced thrombosis prophylaxis of IPC combined with LMWH.
  • IPC is the major modality for those at high risk of bleeding.
  • IPC + properly fit graduated compression stockings may be of value, especially when anticoagulation is contraindicated. 
  • Home compression is a valuable adjunct for those with limited ambulation and multiple co-morbidities.

What is the proposed treatment of venous thrombosis in Covid-19 patients?

An approach based on risk assessment and prevention of VTE is critical and highly recommended in the treatment of NCP. 

Considerations and treatment of venous thromboembolism in COVID-19 patients are as follows:

Step 1: CBC, PC, PT, PTT, D-dimer, and FDP are measured initially and serially elevated. 

  • D-dimers mark the severity of the disease and represent a marker for severe outcomes. 
  • If D-dimer is negative, US screening is necessary.

Step 2: Heparin of LMWH prophylaxis 

  • After risk assessment on admission, all patients should receive heparin of LMWH as prophylaxis due to the high risk of thrombotic complications, including microvascular thrombosis.  
  • LMWH prophylaxis 30mg BID or 40mg QD adjust for renal insufficiency or BMI more than 35. 

Because of how serious all of this is, Prof. Caprini proposed an algorithm for inpatient COVID-19 to determine the type of AC therapy modulated for each patient. He also proposes an algorithm for COVID-19 discharge considerations. 

He also highlighted that ongoing scoring is critical since the updated score often changes in thrombosis prophylaxis, including post-discharge anticoagulant prophylaxis.  




If you like to know more about the Caprini score, explore the dedicated website:

Watch the full session

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