Reporting of d-dimer and harmonization needs: Data from participants to the eqa scheme of the center of biomedical research

ABSTRACT

Introduction: D-Dimer assessment represents a cornerstone in the diagnostic approach of several thrombotic disorders. Recent literature has highlighted the role of D-Dimer also in the diagnostic pathway of COVID-19 and the importance of a harmonized reporting [D-dimer unit (DDU) or fibrinogen equivalent unit (FEU);unit of measure;cut-off] in order to guarantee the correct interpretation of the results1. Purpose and Methods: Evaluation of D-Dimer data from 100 EQA participants and the inter-laboratory variability (CV%) of the last 7 years for the most used analytical systems HemosIL HS, IL-HS (n=37}4), HemosIL HS-500, IL-HS500 (n=8}1), Sclavo Auto, SCLA (n=12}5), Siemens Innovance, INN (n=14}3), bioMerieux VIDAS, VID (n=10}3), Stago STA Liatest, STA (n=10}3). Results: Concerning the results expression in DDU or FEU, there is a prevalence of FEU (55.1%) over DDU (44.9%), value confirmed in the last 7 years (average FEU = 55.6%), differently from data obtained in the survey conducted in 2014 at national level2.The units used are Ng/mL (67.7%), μg/L (29.0%) and mg/L (3.2%) for D-Dimer DDU;ng/mL (57.9%), μg/mL (21.1%), μg/L (15.8%) and mg/L (5.3%) for D-Dimer FEU. Inter-laboratory variability (mean CV%}SD) calculated on a total of 68 control samples (range, μg/L)-D-Dimer, DDU = SCLA 8.8}3.3 (82-170);5.4}2.7% (402-1482);IL-HS 12.8}6.1 (122-166);6.4}2.7% (480-1705).-D-Dimer, FEU = IL-HS 13.9}2.0 (192-340);5.2}2.3 (1016-3158);IL-HS500 5.1}2.6 (1430-3442);INN 11.3}5.6 (191-330);6.3}2.3% (1439-4521);VID 6.9}3.5 (158-378);5.4}2.3 (673-2018);STA 7.1}6.6% (220-385);5.1}2.0% (860-2600). Discussion: This study demonstrates that the reporting of D-Dimer results does not comply with the 2014 SIBioC consensus document which recommended the use of μg/L FEU3, and highlights 8 different types of information. The CV% is lower for all diagnostic systems at pathological levels than the ones at concentrations near to the cut-off. Conclusion: Data reported in this study call for the harmonization of D-Dimer reporting in order to guarantee the correct interpretation of information, both of COVID-19 and all diseases already.