Grand Rounds

Thrombotic Events and COVID-19: How Often do they Occur and What are the Risk Factors?

BACKGROUND AND PURPOSE:

Patients with COVID-19 are at an increased risk of thrombosis although risk factors and incidence remain unclear
Bilaloglu et al. (JAMA, 2020) assessed the incidence and risk factors for venous and arterial thrombotic events in all hospitalized patients with COVID-19 at a large health system in New York City

Case series
Setting
- Four hospitals between March 1 and April 17, 2020
Participants
- Consecutive patients ≥18 years old
- Hospitalized with confirmed COVID-19
Study design
- Thrombotic events were identified from clinical notes and radiology reports
- Venous events: Deep vein thrombosis (DVT) | Pulmonary embolism (PE)
- Arterial events: Myocardial infarction (MI) | Ischemic stroke | Other systemic thromboembolism
- Mortality definition: In-hospital death or discharge to hospice as of June 1, 2020
- Competing risk survival analyses were conducted
Primary outcomes
- Thrombosis
- Mortality

Data from 3334 patients were included
- Median age: 64 (IQR 51 to 75) years | 39.6% female
- Most patients received low-dose (prophylaxis) anticoagulation
Thrombotic event incidence
- Any thrombotic event: 16.0% (533 patients)
- Venous: 6.2% (207 patients)
  - PE: 3.2%
  - DVT: 3.9%
- Arterial: 11.1% (365 patients)
  - Ischemic stroke: 1.6%
  - MI: 8.9%
  - Systemic thromboembolism: 1.0%
Risk factors associated with thrombotic event (adjusted for covariates)
- Age
- Sex
- Hispanic ethnicity
- Coronary artery disease
- Prior MI
- Higher D-dimer levels at hospital presentation
All-cause mortality
- All-cause mortality: 24.5%
- Mortality was higher in those with thrombotic events (P<0.001)
  - With thrombotic events: 43.2%
  - Without: 21.0%
A thrombotic event was independently associated with mortality
- Adjusted hazard ratio (HR) 1.82 (95% CI, 1.54 to 2.15; P < 0.001)
Both venous and arterial thrombosis were associated with mortality
- Venous: adjusted HR 1.37 (95% CI, 1.02 to 1.86; P = 0.04)
- Arterial: adjusted HR 1.99 (95% CI, 1.65 to 2.40; P < 0.001)
ICU patient outcomes
- Thrombotic events: 29.4%
  - Venous: 13.6%
  - Arterial: 18.6%
Non-ICU patient outcomes
- Thrombotic events: 11.5%
  - Venous: 3.6%
  - Arterial: 8.4%

Thrombotic events occurred in 16.0% of hospitalized COVID-19 patients in a NYC health system
- Elevated D-dimer levels at presentation were independently associated with thrombotic events, consistent with early coagulopathy
Thrombotic events in COVID-19 patients may be the result of
- Cytokine storm | Hypoxic injury | Endothelial dysfunction | Hypercoagulability | Increased platelet activity
Study limitations
- Thrombosis may have been underestimated due to judicious use of this modality
Authors note that awareness for thrombotic events increased over course of the study and that with time, anticoagulation became more common

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