Role of von Willebrand Factor in COVID-19 Associated Coagulopathy.

BACKGROUND: COVID-19, the disease caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) can present with symptoms ranging from none to severe. Thrombotic events occur in a significant number of patients with COVID-19, especially in critically ill patients. This apparent novel form of coagulopathy is termed COVID-19-associated coagulopathy (CAC), and endothelial derived von Willebrand factor (vWF) may play an important role in its pathogenesis. CONTENT: vWF is a multimeric glycoprotein molecule that is involved in inflammation, primary and secondary hemostasis. Studies have shown that patients with COVID-19 have significantly elevated levels of vWF antigen and activity, likely contributing to an increased risk of thrombosis seen in CAC. The high levels of both vWF antigen and activity have been clinically correlated with worse outcomes. Furthermore, the severity of a COVID-19 infection appears to reduce molecules that regulate vWF level and activity such as ADAMTS-13 and high-density lipoproteins (HDL). Finally, studies have suggested that patients with group O blood (a blood group with lower baseline levels of vWF) have a lower risk of infection and disease severity compared to other ABO blood groups; however, more studies are needed to elucidate the role of vWF. SUMMARY: CAC is a significant contributor to morbidity and mortality. Endothelial dysfunction with the release of prothrombotic factors, such as vWF, needs further examination as a possible important component in the pathogenesis of CAC.

Laboratory Assay Evaluation Demystified: A Review of Key Factors Influencing Interpretation of Test Results Using Different Assays for SARS-CoV-2 Infection Diagnosis.

Laboratory tests are an integral part of the diagnosis and management of patients; however, these tests are far from perfect. Their imperfections can be due to patient health condition, specimen collection, and/or technological difficulty with performing the assay and/or interpretation. To be useful clinically, testing requires calculation of positive predictive values (PPVs) and negative predictive values (NPVs). During the current global pandemic of COVID-19 (coronavirus disease 2019), multiple assays with unknown clinical sensitivity and specificity have been rapidly developed to aid in the diagnosis of the disease. Due to a lack of surveillance testing, the prevalence of COVID-19 remains unknown. Hence, using this situation as an clinical example, the goal of this article is to clarify the key factors that influence the PPV and NPV yielded by diagnostic testing, By doing so, we hope to offer health-care providers information that will help them better understand the potential implications of utilizing these test results in clinical patient management.