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Abstract 498: Age-adjusted Cut-off Levels Improve Test Performance in the Diagnosis Strategy of Venous Thromboembolism in Elderly Patients With a Non-high Pre-test Probability

BackgroundD-dimer levels below a well defined cut-off level enable to safely rule out VTE in patients with non-high PTP. Ageing is associated with higher levels of D-dimer. To address the issue of their usefulness in elderly patients, we firstly managed data from 644 out-patients with non-high PTP included in a multicenter management study of a D-dimer assay (C.Legnani et al. 2010). We then validated our results in a cohort of 1,042 consecutive patients investigated using another assay. ResultsIn the first part, D-dimer level, evaluated using the HemosIL D-dimer HS500 assay (Instrumentation Laboratory), was above the cut-off level (500 ng/ml) in all 88 patients with VTE and in 299 of those without (53.8%). Test negative predictive value (NPV) and sensitivity were 100%. Overall test specificity was 46.2%, but decreased in an age-dependent manner over 70 y. ROC-analysis of test results obtained in patients classified according to age allowed us to propose an age- adjustment of the cut-off level calculated b...