PB0441 - Assessment of the value of the normalized APC sensitivity ratio in clinical routine practice

Sunday, June 23, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

ND

Nathalie Donis

Project Leader
QUALIblood s.a., QUALI-Research Department, Namur, Belgium
Namur, Namur, Belgium

Co-Author(s)

LM

Laure Morimont

Assay Director
QUALIblood s.a., QUALI-Research Department, Namur, Belgium
Namur, Namur, Belgium
CB

Clotilde Brisbois

Technician
QUALIblood s.a., QUALI-Research Department, Namur, Belgium
Namur, Namur, Belgium
JW

Julie Winand

Project Manager
QUALIblood s.a., QUALI-Research Department, Namur, Belgium
Namur, Namur, Belgium
JD

Jean-Philippe Defour

MD
Clinical Biology Laboratory, Groupe Santé CHC – Clinique MontLegia, Liège, Belgium
Liège, Liege, Belgium
MF

Mélissa François

MD
Clinical Biology Laboratory, Groupe Santé CHC – Clinique MontLegia, Liège, Belgium
Liège, Liege, Belgium
LG

Laure Gilis

MD
Thrombosis, Hemostasis and Cardiovascular Medicine unit, Groupe Santé CHC – Clinique MontLegia, Liège, Belgium
Liège, Liege, Belgium
GS

Geoffroy Senterre

MD
Gynecology-Obstetrics and Maternal Intensive Care units, Groupe Santé CHC – Clinique MontLegia et Clinique CHC Heusy, Liège, Belgium
Liège, Liege, Belgium
JF

Julien Favresse

PhD Student
Department of Laboratory Medicine, Clinique St-Luc Bouge, Namur, Belgium
Namur, Namur, Belgium
JD

Jonathan Douxfils

Project Manager, CEO
QUALIblood sa, QUALI-Research Department, Namur, Belgium
Namur, Namur, Belgium

Background: The ISTH SSC supports the use of endogenous thrombin potential-based activated protein C resistance (ETP-based APC-R) to assess APC resistance. The results of this assay can be expressed as normalized APC sensitivity ratio (nAPCsr) which could be a promising tool to identify women with increased risk of venous thromboembolism (VTE) and guide patient’s treatment and monitoring.

Aims: To report early clinical experience of nAPCsr in gynecology and cardiology units. We compared the nAPCsr with clinical data to assess its value as a decision tool for practitioners.

Methods: ETP-based APC-R was assessed on 56 plasma samples from combined oral contraceptive (COC) non-users to identify normal ranges of nAPCsr. It was then assessed on plasma samples from patients upon physician prescription and their nAPCsr was confronted to clinical parameters: age, COC use, pregnancy status, hereditary thrombophilia, protein S (PS) level.

Results: nAPCsr normal ranges were established between 0.00 and 2.08 in COC non-users. A 28-year-old woman under COC containing EE/DRSP with family history of VTE had a nAPCsr of 5.64. Two women, aged 41 and 42, using EE/CPA and EE/DNG had a nAPCSr of 8.64 and 8.79, respectively. A 29-year-old pregnant woman with personal history of ovarian venous thrombosis during a first pregnancy and low PS level had a nAPCsr of 9.07. Finally, an 18-year-old woman with a heterozygous Factor V Leiden mutation had a nAPCsr of 6.09. Each of these cases led to specific clinical decisions or closer monitoring of the patient for potential prothrombotic conditions which were initially unknown.

Conclusion(s): These results suggest that the nAPCsr permits the identification of patients with APC resistance, whether it is hereditary (e.g. Factor V Leiden) or acquired (e.g. COC- or pregnancy-induced APC-R). The nAPCsr could be used by physicians as a surrogate biomarker to estimate the VTE risk in women and help in clinical decision making.