Comparison of an immuno-turbidometric method (STalia®D-DI) with an established enzyme linked fluorescent assay (VIDAS®) D-dimer for the exclusion of venous thromboembolism

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Abstract

Summary

The use of D-dimer tests for the exclusion of venous thromboembolism is an important advance in clinical practice and also has economic benefits. The Stalia®D-Di (Diagnostica Stago, Asnieres, France) is a semi automated system for the quantification of D-dimer using an immuno-turbidometric method incorporating a suspension of latex microparticles coated with two different monoclonal antibodies specifically targeted against human D-dimer fragments. Results are available rapidly in <10 min compared with 35 min for the established VIDAS®D-dimer automated enzyme-linked immunosorbent assay (ELISA, BioMerieux, Basingstoke, UK). During November and December 2005, 100 consecutive patients attending the outpatient deep venous thrombosis (DVT) clinic were tested using the VIDAS®D-dimer as part of the routine DVT investigation. Using the same samples, D-dimer estimation was also performed on the STalia®D-Di for comparison. Across a wide range of data (Vidas 83–5656) and (STalia® <200–>4000), there was good agreement between the two methods. Using cutoff's of 500 μg/l fibrinogen equivalent units (Keeling et al., 1999), 42% (42/100) patients were negative (<500) and 46% (46/100) were positive (>500) on both systems. Six per cent (6/100) were positive on the Vidas but negative on the STalia® and another 6% (6/100) were positive on the STalia® but negative on the Vidas. In conclusion, 88% (88/100) of patients showed agreement and in the other 12% (12/100), one had a DVT as identified by Compression ultrasonography (CUS). In this study, there were seven patients with a DVT as identified by CUS and they all scored as ‘likely’ on a pretest clinical probability score and so negative D-dimer would not be used clinically to rule out the disease. The Vidas is a well established instrument for D-dimer measurement in outpatient DVT clinics, and in this small study the STalia® compares very well and therefore would fit into an outpatient setting for D-dimer measurement. But ideally a larger study would be required before implementing new methodology in a clinical setting.

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