Prevalence and Severity of Venous Thromboembolism in a General Population During the COVID-19 Pandemic

Study Overview
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Brief Summary
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The purpose of this study is to investigate the prevalence of venous thromboembolism in a regional health care system (Region Östergötland, Sweden) before and during the SARS-COV-2 pandemic. In a retrospective observational study, we will review patient data, diagnostic data and treatment data over a three-month period since the onset of the SARS-COV-2 pandemic. This data will be compared with data from the corresponding time frame during the years 2015 to 2019.

Detailed Description
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In the current SARS-COV-2 pandemic there is a concern about an increased risk of venous thromboembolism (VTE) concurrent with the infection, including both pulmonary embolism (PE) and deep venous thrombosis (DVT) (Klok et al. 2020; Cui et al. 2020; Helms et al. 2020; Leonard-Lorant et al. 2020; Poissy et al. 2020). International guidelines now recommend prophylactic anticoagulation for all hospitalized patients with a SARS-COV-2 infection in the absence of any contraindication (Thachil et al. 2020). The majority of the studies on VTE in SARS-COV-2 infections have been carried out in the ICU and show prevalence of VTE of between 20 and 30%.(Klok et al. 2020; Cui et al. 2020; Helms et al. 2020). This is a clear increase compared to the less than 10 % prevalence seen in other ICU patients (Muscedere, Heyland, and Cook 2007; Deborah Cook et al. 2005; D. Cook et al. 2000). However, a single center study on consecutive ICU patients with severe sepsis showed a prevalence of VTE of 37% (Kaplan et al. 2015) and another recent publication of patients with severe influenza A/H1N1 infection had a prevalence of VTE of 44% (Obi et al. 2019). This raises the question whether the increase in VTE seen in recent publications of SARS-COV-2 infections is the result of the specific pathophysiology of the virus itself or the subsequent sepsis with multiorgan failure seen in most complicated and severe cases. The former would have large implications for patients treated outside the ICU and possibly outside hospitals (Thachil et al. 2020). The aim of this study will be to investigate the prevalence of VTE in a regional healthcare system prior to, and during the SARS-COV-2 pandemic and the differences between ICU, hospitalized and outpatient cohorts.

Official Title
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Prevalence and Severity of Venous Thromboembolism in a General Population During the COVID-19 Pandemic

Conditions
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COVID-19, Venous Thromboembolism, Pulmonary Embolism, Deep Vein Thrombosis, SARS-CoV 2

Intervention / Treatment
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* Diagnostic Test: Diagnostic examination for venous thromboembolism


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Any patient that has done a Computer Tomography Angiography of the lungs between 1:st of March and 31:st of May each year from 2015 to 2020 Any patient that has done a Ultrasound of the legs between 1:st of March and 31:st of May each year from 2015 to 2020 Any patient with a new diagnosis of pulmonary embolism or deep venous thrombosis between 1:st of March and 31:st of May each year from 2015 to 2020 Exclusion Criteria: Incomplete diagnostic examination Follow-up examination of know acute VTE Primary investigation done outside the healthcare system Patient <18 years of age

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| SARS-CoV-2 pos<br>Patients who have been tested positive for SARS-CoV-2 virus by either nasopharyngeal swab PCR or antibody testing. | Diagnostic Test: Diagnostic examination for venous thromboembolism<br>* Patients who have done a diagnostic examination for suspected VTE (pulmonary embolism och deep venous thrombosis) within the health care system of Region Östergötland. Patients without matching diagnostic examination but with a new diagnosis of pulmonary embolism or deep venous thrombosis during the same time periods will also be taking into account.<br>* Other names: Ultrasound for deep venous thrombosis (DVT);|
| SARS-CoV-2 neg<br>Patients without symptoms for SARS-CoV-2 infection who haven't been tested for the virus or patients with symptoms who have been tested negative for SARS-CoV-2 virus by either nasopharyngeal swab PCR or antibody testing. | Diagnostic Test: Diagnostic examination for venous thromboembolism<br>* Patients who have done a diagnostic examination for suspected VTE (pulmonary embolism och deep venous thrombosis) within the health care system of Region Östergötland. Patients without matching diagnostic examination but with a new diagnosis of pulmonary embolism or deep venous thrombosis during the same time periods will also be taking into account.<br>* Other names: Ultrasound for deep venous thrombosis (DVT);|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Is there an increased prevalence of venous thromboembolism in a regional healthcare system in Sweden during the SARS-CoV-2 pandemic? |  | March to May in 2020 | 
| Is a SARS-CoV-2-infection an isolated risk factor for thromboembolism? |  | March to May in 2020 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Are there geographic differences in the prevalence of venous thromboembolism within the healthcare system? |  | March to May in 2020 | 
| Is venous thromboembolism associated with increased mortality adjusted for relevant comorbidities? |  | March to May in 2020 | 
| How long is the time between symptom onset of the SARS-CoV-2-infection and any subsequent venous thromboembolism? |  | March to May in 2020 | 
| Is treatment with prophylactic antithrombotic or anticoagulant treatment associated with increased survival? |  | March to May in 2020 |