Background: As a result of a number of clinical management studies, D-dimer (DD) tests such as VIDAS (BioMérieux Australia P/L-Sydney, NSW) have been recommended to reduce venous thromboembolism (VTE) investigations. Surveillance studies for new tests are recommended. We prospectively assessed VIDAS DD in normal practice.
Methods: Consecutive emergency patients and inpatients (IPs) with DD or VTE investigations were prospectively identified. Investigation results and early chart review including predefined factors reducing specificity were documented. A latex DD was also performed. Patients were followed for at least 3 months for recurrent VTE.
Results: Four hundred three patients (emergency, 64%; VTE-positive, 12%; 95% followed up) were analyzed. VIDAS sensitivity was 96% (95% confidence interval 86%-99%), specificity 38% (confidence interval, 34%-44%; negative likelihood ratio, 0.11), and emergency specificity 51%. Latex sensitivity was 76%. Cancer, trauma, recent operations, IP status, and advanced age were associated with markedly reduced specificity. Specificity in older emergency patients (>70 years old) and younger IPs (<70) without comorbidities was 20% to 30%, but sensitivity was maintained at 100%.
Conclusions: VIDAS DD probably maintains adequate sensitivity in normal clinical practice for low- or even intermediate-risk patients. Latex agglutination had poor sensitivity. Specificity is best in younger low-morbidity emergency patients. These findings need validation in larger multicenter surveillance studies.