The performance of age-adjusted D-dimer cut-off in Chinese outpatients with suspected venous thromboembolism

Background: D-dimer testing has been widely used in the exclusion of venous thromboembolism (VTE), but its clinical usefulness is limited in older patients because of a lower specificity.

Objective: To evaluate the diagnostic performance of STA-Liatest D-dimer assay and validate the age-adjusted cut-off value in Chinese outpatients with suspected VTE in a prospective non-interventional study.

Methods: Symptomatic patients suspected of having deep venous thrombosis or pulmonary embolism were recruited from 2 participating centers. STA-Liatest D-dimer assay, clinical pretest probability assessment and diagnostic imaging test including complete compression ultrasonography or computed tomography pulmonary angiography were performed among all participants. The performance of D-dimer test was assessed with an age-adjusted D-dimer cut-off (age×0.01μg/ml in patients aged>50years) and with conventional cut-off (0.5μg/ml at all ages).

Results: A total of 594 eligible outpatients were included in this study and VTE was diagnosed in 195 (32.8%) patients. In those patients with a low or moderate pretest probability (n=373), the increase in the proportion of patients with a D-dimer below the age-adjusted cut-off value compared with the conventional cut-off value was 5.9% (95% confidence interval; 3.8%-8.7%). The sensitivity, specificity and negative predictive value of STA-Liatest D-dimer test were 95.0% (83.5% - 98.6%), 84.1%(79.8%-87.6%) and 99.3%(97.5% - 99.8%), respectively, using the age-adapted diagnostic strategy.

Conclusions: The application of age-adjusted cut-off of D-dimer test combined with clinical probability greatly increases the proportion of Chinese older outpatients in whom VTE can be safely excluded.