Study challenges common practice: D-dimer test still works for delayed diagnoses

Background: It has been suggested that D-dimer testing should be avoided in patients with prolonged symptoms, as results may yield false negatives. However, the evidence supporting this recommendation is limited. Objectives: This study evaluated the impact of symptom duration on D-dimer and investigated associations between false-negative D-dimer results and prolonged symptoms. Methods: Patients diagnosed with pulmonary embolism, deep vein thrombosis (DVT), or upper extremity DVT between 2005 and 2020 were identified through the Venous Thrombosis Registry in Østfold Hospital (TROLL), Norway. Eligible patients had available D-dimer results and symptom duration data. Correlations between symptom duration and D-dimer were evaluated using Kendall’s τ test. The association between false-negative D-dimer results and symptom duration categories (0-7 days, 8-14 days, and beyond 15 days) was analyzed using the Cochrane–Armitage test. Results: In total 3423 patients were included, of whom 1696 (49.5%) were women, with a median age of 67 years (IQR, 54-78 years). The median symptom duration was 4 days (IQR, 2-10 days), and 946 patients (27.6%) reported symptoms exceeding 1 week. D-dimer showed a weak negative correlation with symptom duration (Kendall τ coefficient = −0.04; P < .001). Overall, 20 patients (0.6%) had false-negative D-dimer results, but these were not significantly associated with symptom duration (P = .55). Conclusion: Although D-dimer were negatively correlated with symptom duration, the coefficient was very weak and unlikely to have clinical relevance. Moreover, false-negative D-dimer results were not associated with prolonged symptoms, suggesting that extended symptom duration may not affect the performance of D-dimer testing in clinical practice.