Validation of an Automated Immunoturbidimetric Assay for Fibrinogen/Fibrin Degradation Products Measurement and its Correlation to a Semi-Quantitative Latex Agglutination Test

Background: Laboratory determination of fibrinogen/fibrin degradation product (FDP) levels is important as a hyperfibrinolytic state marker. The aim of the study was to verify the analytical performance of an automated immunoturbidimetric assay (AIMT) for FDP and its comparison to a latex agglutination semiquantitative (SLAT) test. Methods: Total precision and accuracy was calculated following the EP 15-A2 protocol at two levels of controls. The protocol EP6 was performed for linearity. For semi-quantitative methods comparison, 71 consecutive samples were used. Concordance between methods results in term of positive and negative, and in categories, from <10 to > 160 mu g/mL, was calculated through Cohen kappa coefficient (kappa). Results: Total CV%: low control (10.8 mu g/mL) 8.0 and 3.7 vs. 4.8 and high control (31.3 mu g/mL) 2.7 and 3.8 vs. 3.6, for coagulometer ACL TOP 500 and 300 vs. manufacturer claimed, respectively. Linearity between 0 and 125 mu g/mL showed polynomial fit analysis applicable. When correlating AIMT to SLAT, a good concordance was observed: kappa of results expressed as positive-negative = 79.5% with 90.1% of agreement (p < 0.001), kappa of results expressed as categories = 72.2% (p < 0.001) with 80.3% concordance. Conclusions: AIMT presented good analytical performance, and the concordance with SLAT by comparison of patients' samples results was also good. The implementation of IMMT in the clinical laboratory is suitable and reliable.