PB0600 - ADAMTS13 activity and non-parallel vWF Ristocetin CoFactor activity are associated with severity of COVID-19 infection

Monday, July 11, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

Stephen MacDonald, MPhil

Principal Clinical Scientist
Cambridge University Hospitals NHS Foundation Trust
Cambridge, England, United Kingdom

Co-Author(s)

DW

Danielle White

Senior Biomedical Scientist
Cambridge University Hospitals NHS Foundation Trust
Cambridge, England, United Kingdom
SC

Sally Cox-Morton, MSc

Senior Biomedical Scientist
Cambridge University Hospitals NHS Foundation Trust
Cambridge, England, United Kingdom
MS

Megan Sharp, MSc

Specialist Biomedical Scientist
Cambridge University Hospitals NHS Foundation Trust
Cambridge, England, United Kingdom
ED

Emily Duff

Specialist Biomedical Scientist
Cambridge University Hospitals NHS Foundation Trust
Cambridge, England, United Kingdom
CB

Christopher Bridgeman

Trainee Biomedical Scientist
Cambridge University Hospitals NHS Foundation Trust
Cambridge, England, United Kingdom
Tara Edwards, MSc

Clinical Scientist
Cambridge University Hospitals NHS Foundation Trust
Cambridge, England, United Kingdom
CM

Chloe Moore

Apprentice Scientist
Cambridge University Hospitals NHS Foundation Trust
Cambridge, England, United Kingdom
EV

Enric Vilar

Consultant Nephrologist
Univeristy of Hertfordshire
Hatfield, England, United Kingdom
MB

Martin Besser

Consultant Haematologist
Cambridge University Hospitals NHS Foundation Trust
Cambridge, England, United Kingdom
ES

Emily Symington

Consultant Haematologist
Cambridge University Hospitals NHS Foundation Trust
Cambridge, England, United Kingdom
MR

Mark Robinson

Consultant Haematologist
Cambridge University Hospitals NHS Foundation Trust
Cambridge, England, United Kingdom
William Thomas, MB BS

Consultant Haematologist
Cambridge University Hospitals NHS Foundation Trust
Cambridge, England, United Kingdom

Background: Increased von Willebrand factor (VWF) is common in COVID-19 infection. vWF levels are reported at levels where pre-dilution of samples is required. The assumption is that such dilutions respond linearly across the measurement range, and that this response is consistent across patient subgroups. ADAMTS13 levels have also been reported as reduced in those most severely affected. The interaction of these biomarkers has potential consequences to understanding pathophysiology of COVID-19.

Aims: To investigate the linearity of dilution of high VWF levels in patients with COVID-19
To compare the response in those mildly affected to those requiring more intensive therapy

Methods: This is a laboratory bases study investigating a convenience sample of fifty age and gender matched patients hospitalised during the first wave of the COVID-19 pandemic (March to June 2020). Patients had been hospitalised for >24 hours before enrolment. Platelet RiCof activity was using the VW Select assay (BioData Corps, Horsham, USA). Dilutions were made using assay buffer provided in the kit.

Data was collected in Microsoft Excel, before being analysed in both Microsoft Excel and the statistical programming environment R (R Core Team (2021)).

Results: The findings of Mancini et al were replicated here in that locale of patient admission was associated with a statistically significant reduction of ADAMTS13 activity (ITU mean 60.21 v non-ITU mean 92.23). The activity of ADAMTS13 remained within what would be a reference range for diagnosis of TTP.
VWF activity by Platelet RiCof was markedly raised. Serial dilution of samples demonstrated non-parallelism, the response being most marked in severely affected patients.

Conclusion(s): Very high VWF levels disrupt the balance with mildly reduced ADAMTS13. In severe COVID-19 infection, the effect manifests as non-parallelism in platelet RiCof parameters. This calculated parameter classifies patients both by presence and severity of disease across all parameters in the platelet Ristocetin CoFactor assay.