Age and gender specific cut-off values to improve the performance of D: -dimer assays to predict the risk of venous thromboembolism recurrence.

The Prolong study shows that continuing vitamin K antagonists (VKA) in patients with abnormal D: -dimer (evaluated by a qualitative assay, Clearview Simplify D: -dimer) results in a significant reduction of venous thromboembolism (VTE) recurrence. The present study retrospectively analyzes a subgroup of patients enrolled in the Prolong study with a view to calculate cut-off values for six quantitative D: -dimer methods to predict the risk of VTE recurrence. We measured D: -dimer levels by VIDAS D: -dimer Exclusion (bioMerieux), STA Liatest D: -dimer (DiagnosticaStago), HemosIL D: -dimer and HemosIL D: -dimer HS (Instrumentation Laboratory), Innovance D: -dimer (Siemens) and AutoDimer (Trinity Biotech) in frozen plasma aliquots sampled 30 ± 10 days after VKA cessation in 390 patients enrolled in the Prolong study. During follow-up (562.7 years), 28 patients had recurrent VTE (7.2%, 5.0% person-years). Since D: -dimer levels are positively correlated with age and significantly lower in men, we calculated method-specific cut-off values according to age and gender. The HRs for VTE recurrence calculated using method-specific cut-off values based on age and gender are higher than those using cut-off values indicated by the manufacturers for VTE exclusion in symptomatic outpatients. These data suggest that method-specific cut-off values calculated according to patient age and gender can be more accurate in identifying patients at a higher risk for VTE recurrence. These method-specific cut-off values are being evaluated in the ongoing prospective management multicenter DULCIS study.