Assessment of the Agreement between the International Normalised Ratio (INR) Values Obtained by Applying Two Different Reagent/Instrument Combinations

AGAZZONI M; INGRATTI M; SÁNCHEZ LUCEROS A; ROMERO ML; REMOTTI L; VERA MORANDINI M; GROSSO S; BLANCO A

Dublin

Congreso; 64th Annual Scientific and Standardization Committee (SSC); 2018

International Society on Thrombosis and Haemostasis, Scientific and Standardization Committee (SSC)

Background: The INR is assessed to monitor patients on antivitamin K treatment (AVK). Aims: The agreement between INR values obtained with 2 different thromboplastin /instrument combinations was evaluated.Methods: INR was determined in 21 normal controls and 245 patients on AVK (acenocoumarol), using either NeoplastineR (NeoR) (Diagnostica STAGO) or ThromborelS (ThrS) (Siemens Health Care Diagnostics) on STA-Compact(Diagnostica STAGO). Reagents were either pre-calibrated (NeoR) or locally calibrated (ThrS). NeoR?s INR values were considered as reference values and patients were grouped according to them in 4 categories I-INR2-4 (therapeutic range), II-INR> 4, III-INR>5 and IV-INR> 6. In addition, INR values were subjectively considered as: A-underdose (≤1.9), B-borderline/low (>1.9-2.1),C-in the therapeutic range (>2.1-3.8), D-borderline/high (>3.8-4.2) andD-overdose (>4.2). Data were analysed applying the Spearman correlationtest, the Bland-Altman plot and the Cohen?s Kappa coefficient.Results: Overall, good correlation between NeoR?s INR values and ThrS?sINR values were observed (r: 0.94; CI: 0.92-0.95; P5, r: 0.78; INR>6, r: 0.53). The mean of the differences between the INR values for NeoR and ThrS in the different groups, the limits of agreement as well as Cohen′s Kappa coefficients are displayed in the table.Conclusions: The agreement between the 2-different thromboplastin/instrument combinations was good to classify patients and normal controls. However, the strength of agreement was moderate among patients under anticoagulant treatment and it was poor for those with INRs over the therapeutic range. NeoR?s values were commonly higher than ThrS?s values, suggesting a possible different sensitivity to coagulation factors or a bias in the calibration procedure.Reach the World Travel Grant