The association between the biomarker D-dimer and thrombosis in vein segment 5 among patients with first episode of deep vein thrombosis

OBJECTIVE: Precise anatomical localization of lower extremity Deep Vein Thrombosis (DVT) has been advocated to improve diagnostic characterization and risk stratification beyond the traditional proximal-distal classification. The objective of this study was to examine whether first-episode DVT involving segment 5 veins differs from non-segment 5 DVT with respect to d-dimer levels and clinical characteristics. METHOD: In this retrospective observational study at Copenhagen University Hospital-Amager and Hvidovre, Denmark, from March 1st, 2017 to February 28th, 2019, we included patients with first-episode lower extremity DVT admitted to the Emergency Department. Patients were divided into two groups: segment 5 vein thrombosis and non-segment 5 vein thrombosis. Differences in d-dimer levels between the groups were analyzed using unadjusted and adjusted linear regressions models with d-dimer as the dependent variable. RESULTS: Of 150 patients with a first-episode lower extremity DVT, 147 had available d-dimer measurements. d-dimer levels were significantly higher in patients with segment 5 vein thrombosis than with Non-segment 5 vein thrombosis. In the unadjusted analysis, mean d-dimer levels were 5.2 Fibrinogen Equivalent Units higher (CI: 2.2:9.8, p = 0.012). After adjustment, this difference increased to 6.5 Fibrinogen Equivalent Units (CI: 1.0:13.0, p = 0.041). These findings suggest that Segment 5 vein thrombosis is associated with increased thrombus degradation and a higher inflammatory burden. This may have significant implications for future risk stratification and the clinical management of DVT. CONCLUSION: First-episode Segment 5 vein thrombosis was associated with significantly higher d-dimer levels than Non-segment 5 vein thrombosis.