English 
Italian Modalità di refertazione del D-Dimero e prestazioni dei sistemi analitici: quali informazioni dal programma di Valutazione Esterna di Qualità del Centro di Ricerca Biomedica
Reporting of D-Dimer and performance of analytical systems: data from participants to the External Quality Assessment Scheme of the Biomedical Research Centre in Italy
AUTORI
1Centro di Ricerca Biomedica per la Qualità in Medicina di Laboratorio, Azienda Ospedale – Università, Padova, Italia
2Dipartimento di Medicina di Laboratorio, Azienda Ospedale – Università, Padova, Italia
Questo lavoro è stato in parte presentato al 52° Congresso Nazionale SIBioC, 6-8 Ottobre 2020, Virtual Edition, quale Comunicazione Orale
ABSTRACT
Reporting of D-Dimer and performance of analytical systems: data from participants to the External Quality Assessment Scheme of the Biomedical Research Centre in Italy
Introduction: D-Dimer assessment represents a cornerstone in the diagnostic approach to several thrombotic disorders. Recent literature has highlighted the role of D-Dimer also in the diagnostic pathway of coronavirus infection (COVID-19) and the importance of 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 results.
Methods: D-Dimer data from 100 EQA participants and the inter-laboratory variability (CV%) of the last 7 years for the most used analytical systems: Werfen, HemosIL HS; Werfen, HemosIL HS-500; Auto D-D, Sclavo; Innovance, Siemens; VIDAS, bioMérieux and STA Liatest, Stago have been evaluated.
Results: concerning the results expression in DDU or FEU, we observed a prevalence of FEU (55.1%) over DDU (44.9%); the value was confirmed in the last 7 years (average FEU = 55.6%), differently from data obtained in the survey conducted in 2014 at a national level.
The units used are: ng/mL (67.8%), μg/L (29.0%) and mg/L (3.2%) for D-Dimer DDU; ng/mL (57.9%), μg/mL (21.0%), μg/L (15.8%) and mg/L (5.3%) for D-Dimer FEU.
Inter-laboratory variability (mean CV%) calculated on a total of 72 controls is lower for all diagnostic systems at pathological levels than the one observed for concentrations below the cut-off.
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 FEU, and highlights 8 different types of information. Data reported in this study call for the harmonization of D-Dimer reporting in order to guarantee the correct interpretation of the information, both in the case of COVID-19 and in all the diseases already known where this analyte has a clinical relevance.