Diagnostic value of D-dimer in patients with a moderate pretest probability of deep venous thrombosis

The negative predictive value (NPV) of d-dimer (DD) for the exclusion of venous thromboembolism is, overall, high and tends to increase as clinical pretest probability decreases. We have assessed the accuracy of a diagnostic protocol including clinical evaluation and DD in 134 outpatients presenting with a moderate pretest probability of proximal deep venous thrombosis (DVT). In these patients, a negative DD value safely excluded DVT (NPV 100%, 95% CI 85-100) In our experience, these results are equivalent to those found for low-pretest probability patients and therefore the same diagnostic strategy can be used for both risk groups.