Exclusion and diagnosis of deep vein thrombosis by a rapid ELISA D-dimer test, compression ultrasonography, and a simple clinical model

Comparative evaluation of d-dimer assays for exclusion of deep venous thrombosis in symptomatic outpatients

Diagnostic work-up of patients sent to the hospital for diagnosing of deep venous thrombosis (DVT) often combines the determination of D-dimer and the application of a clinical probability score. To fulfill diagnostic as well as economic needs, D-dimer assays should exhibit a high negative predictive value (NPV) as well as reasonable specificity. In this study, we evaluated both a latex-enhanced immunoassay for use on routine coagulation analyzers and a radial partition immunoassay (RPIA) for use on a point-of-care analyzer. Samples included were from 344 outpatients with suspected deep venous thrombosis. Among them, 100 had deep venous thrombosis. Results obtained for both assays show a good efficiency for exclusion of deep venous thrombosis with well-acceptable specificity.

[Deep venous thrombosis of lower extremities in an Emergency Department. Utility of a clinical diagnosis model]

BACKGROUND

Deep vein thrombosis (DVT) is a difficult to diagnostic disease. The aim of this study was to determine the utility and accuracy of a risk stratification questionnaire and a diagnostic strategy, which were applied to patients with suspected DVT on lower extremities in an emergency department.

PATIENTS AND METHOD

A prospective cohort study was performed in 569 outpatients with clinical suspected DVT during 14 months. The applied questionnaire stratified patients into three pre-test probability categories. Items included signs, symptoms, risk factors and potential alternative diagnosis, which were based on a modified Wells clinical model. DVT was diagnosed by the combined use of clinical model, compression ultrasonography (CUS) and follow-up CUS one week later in those moderate-high risk patients with an initial normal test. These patients were followed over three months for the development of venous thromboembolic complications.

RESULTS

Two hundred three (35.7%) patients were classified as having a low, 186 (32.7%) moderate and 180 (31.6%) high clinical probability. Overall, DVT was diagnosed in 153 patients (26%; CI95%, 23.2-30.7%): 144 (96%) at the initial CUS, 6 (3.5%) at the second testing and 3 over the 3-month follow-up period. 22 patients had a low pretest probability (11%; CI95%, 7-16%), 43 (23%; CI95%, 17-30%) moderate, and 88 (49%; CI95%, 41-56%) high pretest probability. The difference in the prevalence of DVP among risk categories was significant (p < 0.00001). When the high and moderate groups were joined, the model had a 86% sensitivity, a 90% negative predictive value and a 43% specificity for diagnosis of DVT.

CONCLUSIONS

The clinical model used in this study is accurate and feasible, though it is not enough to take clinical decisions. The diagnostic strategic used is effective but not efficient.

Rapid ELISA D-dimer testing in the exclusion of venous thromboembolism in hospitalized patients

The clinical diagnosis of deep-vein thrombosis (DVT) and pulmonary embolism (PE) is known to be unreliable. Until now, no biological marker has been found to confirm thrombosis, but help can be gained from a biological marker ruling out the diagnosis of DVT or PE, i.e., the sensitive measurement of D-dimer (DD) species. This article summarizes our experience in introducing a rapid D-dimer test (ELISA VIDAS D-dimères test, bioMérieux) in a collaborative strategy for thrombosis diagnosis during 9 consecutive months involving 1,131 measurements. The efficacy of the DD test was very different according the type of patient, and departments where the DD test provides a real diagnostic benefit were identified. High clinical probability for thrombosis was encountered in 32 patients and radiology was carried out, although D-dimer was negative: none of these patients was found to have a thrombosis after radiologic examination. However, extensive progress must be made in test prescription to reduce the excessive rate of positive D-dimer tests (78%) and positive measurements that are not followed up by radiology (42%).