Comparison of Two Quantitative D-Dimer Tests for Venous Thromboembolism Exclusion in the Emergency Department Setting

Abstract

Venous thromboembolism (VTE) is a prevalent cause of emergency department visits in the US. VTE algorithms that incorporate pretest probability assessment, D-dimer testing and non-invasive imaging may be used for VTE exclusion in this outpatient setting. We evaluated the performance of a new automated HemosIL D-Dimer HS500 in samples from our emergency department for suspected VTE and compared its results to VIDAS D-Dimer Exclusion (Biomerieux, Durham, NC) assay. HemosIL DDHS500 is an automated, latex enhanced turbidimetric immunoassay tested on the ACL TOP coagulation analyzer (Instrumentation Laboratories, Lexington, MA). Consecutive samples from the Emergency Department with suspected VTE were tested from 11/2012-01/2013 at our institution. Testing was performed according to laboratory and manufacturer procedures. Statistical analyses were performed using EP Evaluator (Data Innovations, South Burlington, VT) for quantitative and qualitative method comparison. For quantitative method comparison the linearity range was used from the manufacturer's package insert (DDimer HS500 linearity range of 215-129,000ng/mL FEUs; VIDAS D-Dimer Exclusion linearity range of 35-5,000 ng/mL FEUs). For qualitative method comparison the VTE clinical cutoff per manufacturer package insert was used (>=500ng/mL FEU for both assays). Correlation studies between HemosIL DDHS500 and VIDAS D-Dimer Exclusion were performed. A total of 151 consecutive samples were tested; 19 of these were outside linearity limits and were excluded with a resultant quantitative method comparison correlation coefficient (R) of 0.89. For the qualitative method comparison all 151 samples were analyzed with a total agreement = 92.7% (140/141), positive agreement = 95.6% (86/90), negative agreement = 88.5% (54/61) and a Cohen kappa = 84.8%. We found acceptable correlation between these two D-dimer methodologies that may be used to aid in the exclusion of VTE in the emergency department setting. Additional clinical performance should be appropriately validated on the HemosIL DDHS500 before use in our clinical laboratory. CORRECTION (February 2014):The correct list of authors should be