THE USE OF 2 DIFFERENT APC RESISTANCE ASSAY SYSTEMS PROVIDES OPTIMAL SENSITIVITY AND SPECIFICITY FOR DIAGNOSING GENETIC APC RESISTANCE

We compared the performance characteristics of a commercial dilute Rus sell's viper venom (DRVV)-based APC resistance assay (Gradipore PC Imp edance Test) to a routinely utilized commercial APTT based assay (Coat est APC Resistance Assay), The DRVV based assay offers improved sensit ivity and specificity for the factor V Leiden mutation. However, the r outine use of both assays provides optimum reliability for diagnosis o f genetic APC resistance. Our results suggest that when both tests are either positive or negative, DNA anal, sis is unnecessary. Interferen ce by lupus anticoagulants is dramatically minimized by the phospholip id rich DRVV reagent used in the assay and it is insensitive to high f actor VIII activity. Additionally, discrepant functional assay results allow identification of patients who may have an acquired APC resista nt phenotype.