Introduction: The exclusion of deep venous thrombosis (DVT) by pre-test probability (PTP) and D-dimer in the elderly is safe, but has a low specificity. There is increasing interest in the diagnostic role of thrombin generation in patients with thrombosis. We evaluated the value of thrombin generation in the exclusion of DVT, especially in elderly patients.
Material and methods: All thrombin generation parameters of the Endogenous Thrombin Potential assay were tested retrospectively in a cohort of 443 patients suspected for DVT. The performance of the assay was calculated as AUC of the ROC curve and association with DVT as odds ratio (OR). The lag time value was combined with results of PTP and Innovance D-dimer assay.
Results: All thrombin generation parameters had a low AUC. In the 4th age quartile, the corrected OR of lag time increased to 16 and the AUC of lag time for the combination PTP < 2 and D-dimers ≥ 500 μg/L was 0.96 with a cut-off value of 23.0 sec. The exclusion of DVT in patients ≥ 75 years (n = 30), based on this combination and lag time values ≤ 23.0 sec had a NPV of 100% and a specificity of 96.0% in this subgroup of patients and decreased the number needed to test from 10 to 1.1.
Conclusion: Thrombin generation parameters alone are inappropriate for the exclusion of DVT. However, in the elderly, the current algorithm of exclusion of DVT may improve markedly by the addition of the lag time results of the ETP.