Deep vein thrombosis in SARS-CoV-2 pneumonia-affected patients within standard care units: Exploring a submerged portion of the iceberg

The outbreak of the coronavirus disease 2019 (COVID-19) spread rapidly throughout the world during the first months of 2020 reaching the pandemic status as a major global health issue. The main clinical and therapeutic concerns due to COVID-19 relate to the respiratory distress and failure caused by pneumonia due to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) [1]. COVID-19, however, is not just a pulmonary disease. While respiratory complications and systemic inflammation unquestionably result in significantly higher morbidity and mortality rates, cardiovascular complications are also common [2]. A number of cohort studies described an association with coagulopathy and venous thromboembolism (VTE) among SARS-CoV-2 infected patients [3]. SARS-CoV-2 predisposes to thrombotic events by means of different mechanisms such as hypoxia, inflammation, prolonged immobilization occurring in the context of different and various alterations of hemostatic pathways (e.g. from endothelial dysfunction to platelet activation, from inflammation-related and consumptive coagulopathy to thrombotic microangiopathy) [4]. Alterations of prothrombin time, fibrinogen, and D-dimer are often observed in COVID-19 patients and are associated with a detrimental outcome [5]. D-dimer has been specifically proposed as a potential prognostic marker, where high D-dimer levels predict higher in-hospital mortality in COVID-19 patients [6]. Consistently, anticoagulant and fibrinolytic drugs have been proposed as possible therapeutic tools [5]. Two studies in Chinese and Dutch populations showed a remarkably high cumulative incidence of symptomatic VTE in patients admitted to the Intensive Care Units (ICU) [7,8]. The prevalence of deep vein thrombosis (DVT) in patients hospitalized for SARS-CoV-2 infection remains, however, not well defined, especially for those admitted to COVID-19 Standard Care Units (SCU). Therefore, we designed a study with the aims of assessing the prevalence of DVT among subjects with SARS-CoV-2 pneumonia in the setting of SCU and investigating the clinical and laboratory characteristics associated with DVT in COVID-19 patients.