Testing for D-dimer to shut out ve...

Testing for D-dimer to shut out venous thromboembolic disease has been available since the 1980 unless the clinical role of this example remains unclear because of the variety of available assays and relate tos about their sensitivities and specificities. Stein and associates reviewed the available evidence onward each of the various D-dimer assays.

Using prospective studies of controll populations where sensitivity and specificity data were not away or could be calculated, studies were disposeed by the type of D-dimer assay used, the cutoff points for positive examples and whether D-dimer was used to debar pulmonary embolism (PE) or of great depth venous thrombosis (DVT).

DVT analyses set up that, in terms of sensitivity, the enzyme-linked immunosorbent assay (ELISA) was clinically and statistically superior to the the quantitative latex agglutination and semi-quantitative latex agglutination assays. For specificity, the quantitative latex agglutination and whole-blood agglutination ordeals were clinically and statistically superior to the ELISA assay. ELISA testing had a high negative likelihood ratio, which give a high certainty for a negative diagnosis. The estimated positive likelihood ratios for principally of the tests are poor; a positive touchstone does not increase the certainty of a positive diagnosis. PE analyses institute similar clinical and statistical characteristics as the DVT analyses, with the ELISA assays having powerful negative likelihood ratios. The greatest in quantity commonly examined D-dimer cutoff value was 500 ng by means of mL, although some data were available for cutoff values of 250 ng by mL and 1,000 ng through mL.

The authors judge that the ELISA and qualitative rapid ELISA exhibitions have the least variability and best sensitivity and ability to method out DVT and PE. The specificity values of the various standards were not adequate to have clinical value in altering the probability of disease, making D-dimer testing a unidirectional test: a negative proceed is useful to exclude DVT or PE moreover a positive result does not necessarily indicate the appearance of disease. The negative ELISA assay provides a negative likelihood ratio similar to those of a normal perfusion lung scan or a negative Doppler ultrasonography finding, making the ELISA assay usable as a stand-alone standard The other assays do not have the same accuracy. Certainly, final diagnostic accuracy is enhanced through using the D-dimer assay in a diagnostic pathway that also identifies pre-testing clinical probability for DVT or PE

In a commentary in the same issue, Sox points disclosed the importance of determining the pretest probability of DVT to optimize the D-dimer assay deduction In patients with a high pretest probability of disease, a negative D-dimer ordeal may not be enough to support forgoing anticoagulation therapy.

Stein PD et al. D-dimer for the exclusion of acute venous thrombosis and pulmonary embolism. A systematic review. Ann Intern M April 20 2004;140:589-602 and Sox HC Commentary. Ann Intern M April 20 2004;140:602

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