Basic Evaluation of the Newly Developed "Lias Auto P-FDP" Assay and the Influence of Plasmin-α2 Plasmin Inhibitor Complex Values on Discrepancy in the Comparison with "Lias Auto D-Dimer Neo" Assay

BACKGROUND: Laboratory determination of fibrin/fibrinogen degradation products (FDP) levels, along with that of the D-dimer, is important for assessing the fibrinolytic situation. Recently, we developed a new FDP reagent "Lias Auto P-FDP", which can detect various FDP fragments. The purpose of this study was to evaluate the basic performance of the newly developed Lias Auto P-FDP and compare it with Lias Auto D-Dimer Neo assay. METHODS: The within-run precision of Lias Auto P-FDP and Lias Auto D-Dimer was determined 20 times in low and high value controls. The between-day precision was evaluated five times a day for five days. The linearity study was performed by diluting high value samples for 2 - 10-fold and 2 - 8-fold. The comparative study was performed using 172 patient samples with elevated FDP values. For the discrepancy analysis, the samples were divided into three groups by the discrepancy percentage between the FDP and D-dimer values. The groups were defined as follows: lower discrepancy group, less than -20%; no discrepancy group, -20% to 20%; upper discrepancy group, more than 20%. RESULTS: The coefficient of variation % (CV%) in within-run and between-day precision were within 3.8% for both FDP and the D-dimer. The correlation coefficients were more than 0.999 and the linearity was high. In the comparative study, the values of FDP were higher than that of the D-dimer in all samples. The median FDP and D-dimer values of lower discrepancy, no discrepancy, and upper discrepancy groups were 11.8, 20.3, and 51.4, and 8.0, 11.3, and 13.1, respectively. FDP showed an increasing tendency but D-Dimer showed constant values. Thus, the possible cause of discrepancy between FDP and D-dimer values were the elevated FDP values. In addition, the values of plasmin-α2 plasmin inhibitor complex (PIC) in the upper discrepancy group were higher than that of the lower and no discrepancy groups, indicating progression of fibrinolysis. CONCLUSIONS: In this study, we evaluated the newly developed Lias Auto P-FDP reagent and confirmed that the basic performance was acceptable. FDP was elevated in samples with high PIC values, which indicated progression of fibrinolysis. Determination of fibrinolysis conditions by FDP measurement is important.