The Fibrin Assay Comparison Trial (FACT) - Evaluation of 23 quantitative D-dimer assays as basis for the development of D-dimer calibrators

Although D-dimer has gained widespread clinical use as a parameter for dete ction of in vivo fibrin formation, the issue of standardization of D-dimer assays remains to be resolved. The FACT study was performed to generate bas ic data for development of calibrators and standard preparations. A set of 86 samples, including plasma samples from patients with DIG, DVT, and other clinical conditions, serial dilutions of pealed plasma samples, a nd plasma samples containing fibrinogen- and fibrin derivatives, were distr ibuted to 12 manufacturers of D-dimer assays. D-dimer assays differ concerning specificity for crosslinked fibrin, and pr eference for either high molecular weight fibrin complexes, or low molecula r weight fibrin degradation products. Terminal plasmin digests of fibrin cl ots for calibration produce aberrant results in some assays, especially tho se with preference for high molecular weight crosslinked fibrin derivatives . The best conformity is achieved by the use of pooled plasma samples from patients with high levels of D-dimer antigen in plasma. in vitro preparatio ns containing a comparable composition of fibrin derivatives to clinical pl asma samples may also serve as reference material.