The fibrin assay comparison trial (FACT): Correlation of soluble fibrin assays with D-dimer

Soluble fibrin (SF) is regarded as an indicator of acute fibrin formation a nd a precursor of fibrin thrombi. Using a set of clinical plasma samples, a nd fibrin derivatives, five assays for measurement of SF, including two chr omogenic assays, two ELISA systems, and one latex-enhanced photometric immu noassay were compared. Correlation between SF assays was moderate (Spearman 's rho values between 0.344 and 0.805). Re-calibration with serial dilution s of desAABB-fibrin monomer resulted in adjustment of the numerical scale o f the assays without improving correlation. All SF assays reacted with purified crosslinked fibrin derivatives, Using c linical plasma samples, Spearman's rho of SF assays with D-dimer consensus values based upon results of 23 quantitative D-dimer assays were between 0. 491 and 0.911. Although all SF assays react with desAABB-fibrin monomer complexes, SF assa ys are heterogeneous concerning reactivity with fibrin compounds observed i n clinical plasma samples. The prospect of a common calibrator for SF assay s therefore seems to be remote. Since SF assays, react with crosslinked fibrin derivatives, it is not possi ble to clearly distinguish between acute fibrin formation, and fibrin disso lution on the basis of the results of current SF assays.