PB0432 - Identification of a Subset of Thrombotic Antiphospholipid Syndrome Patients with Significant Discordance in paired Capillary- and Venous- Monitoring with an International Normalized Ratio

Sunday, June 25, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

Nuria Revilla, MD, PhD

Hospital Universitario Fundación Jiménez Díaz, Instituto Investigación Sanitaria FJD (IIS-FJD) Madrid, Spain.
Madrid, Madrid, Spain

Co-Author(s)

RV

Rosa Vidal-Laso

Hematologist
Hospital Universitario Fundación Jiménez Díaz
Madrid, Madrid, Spain
IM

Inés Martínez-Alfonzo

Hematologist
Hospital Universitario Fundación Jiménez Díaz
Madrid, Madrid, Spain
DV

Diego Velasco-Rodríguez, PhD, MD

Hematologist
Hospital Universitario Fundación Jiménez Díaz
Madrid, Madrid, Spain
IB

Inmaculada Burgos-Trillo

NP
Hospital Universitario Fundación Jiménez Díaz
Madrid, Madrid, Spain
SM

Sara Martín-Herrero

Hematologist
Hospital Universitario Fundación Jiménez Díaz
Madrid, Madrid, Spain
CL

Carmen López-Álvarez

NP
Hospital Universitario Fundación Jiménez Díaz
Madrid, Madrid, Spain
PL

Pilar Llamas-Sillero

Hematologist
Department of Hematology, Hospital Universitario Fundación Jiménez Díaz, Instituto Investigación Sanitaria FJD (IIS-FJD), Madrid, Spain
Madrid, Madrid, Spain

Background: Patients with antiphospholipid syndrome (APS) typically require vitamin K antagonists (VKA) anticoagulation following a thrombotic event. Point of care testing (POCT) reagents to monitor international normalized ratio (INR) may falsely influence results and lead to subtherapeutic doses in APS patients.

Aims: We aimed to investigate whether a systematic difference exists between POCT-INR an plasma-INR in patients with thrombotic APS.

Methods: We retrospectively compared 337 paired POCT- (CoaguChek, Roche) and plasma-INR Quick method (HemosIL Recombiplastin 2G, Werfen) results from 88 thrombotic APS patients (Sydney classification criteria), receiving VKA (83 acenocumarol, 5 warfarin) with each patient having a minimum of three simultaneously paired measurements with POCT-INR >1.9 and < 4.6. An acceptable variation was determined to be < or equal to 0.5 INR units (INR agreement), identifying patients with at least two paired measurements > 0.5 variation in INR units as “INR disagreement”.

Results: A strong positive correlation was found between paired POCT- and plasma-INR (Spearman’s=0.858, p< 0.001). 88.6% of patients were considered INR agreement. INR disagreement was found in 11.4% patients, with higher POCT-INR in the majority (8/10). These comparisons lead us to make a change in the VKA monitoring in 20.5% of APS due to patient preference or significant discordances: increase in the POCT-INR therapeutic range (n=12) or continued with only plasma-INR monitoring (n=6).
Clinical and biological characteristics are summarized in Table1. We did not find any significant difference between clinical characteristics. Interestingly, we observed more Antib2-glycoprotein-I antibody (Ab2GPI) IgG positive patients (40.0% vs. 16.7%,p=0.080) and significant more Anti-cardiolipin antibody (aCL) IgG (60.0% vs. 19.2%,p=0.018) in INR disagreement group. Three patients had systematic differences about 1.0 (0.90-1.50) higher POCT-INR. All of them were women and triple positive (aCL-IgG and Ab2GPI-IgG positives).

Conclusion(s): Systematic comparison of a minimum three paired INR measurements is recommended before implementing POCT-INR monitoring in any APS patient, especially with aCL-IgG-positive.