A comparison study of the Helena Auto Red D-dimer 700 Against the SIEMENS INNOVANCE® D-dimer assay
University of Wales Institute Cardiff
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Aims Deep vein thrombosis which leads to pulmonary embolism of the lung is a frequent cause of death in hospitalised, bed-ridden and immobilized patients. Its long term disability cost is a burden on the National Health Service. Due to this burden a reliable and cost effective test with short turnaround times needs to be utilised as a diagnostic tool. This study compares and evaluates the analytical and diagnostic performance of two fully automated D-dimer assays, the Helena Bioscience Auto Red D-dimer 700 and the SIEMENS INNOVANCE® D-dimer assay. The manufacturer claim that the Innovance assay has greater diagnostic sensitivity was also investigated in conjunction with specificity in order to deduce a valid conclusion. Methods Comparison was made by collecting 190 citrated plasma samples with requested D-dimer tests and analysing the samples using both the Helena and SIEMENS assay, and using the data in correlation studies. Analytical performance in terms of accuracy and precision were determined by repeating Internal Quality Control material 8 times for high and low range values. Results Correlation studies yielded strong positive correlation (r = 0.9301) between the two assays, indicating a strong relationship. A paired t-test revealed a p-value of <0.0001 which is <0.05 therefore there is a low probability that the association arose by chance. Of the 190 samples, only 170 were assayed due to exclusion of concentrations outside the measuring range, 96% were comparable for the Helena assay and 89% were comparable for the Siemens assay, suggesting a higher analytical sensitivity for the Helena assay. Both assays performed within ± 2 SD of the mean with regards to accuracy and precision, however the Helena assay yielded results of greater accuracy, with SD differences of 13.6ng/mL and 113ng/mL for QC low and QC high respectively, and greater precision with differences of 5.3% and 1.3% CV for QC low and QC high. Clinical performance resulted in 60% of the samples being classified as normal for the Helena assay and 46% normal for the SIEMENS assay, leading to a 14% increase in scans. The sensitivity for the SIEMENS assay was said to be 99.5 - 98.7% on the Sysmex CA-1500 with specificity of 39.3 - 35.9%. Sensitivity is lower for the Helena assay at 95% but specificity is higher at 64% leading to less false positives. Conclusion For this comparison study, the overall performance of the SIEMENS INNOVANCE D-dimer was inferior to that of the Helena Auto Red D-dimer 700, particularly with regards to accuracy and precision. The SIEMENS high sensitivity makes the assay suffer in terms of specificity, which in is important in an exclusion test. The combination of high sensitivity and low specificity leads to false positives, leading to expensive follow up testing which can be inappropriate.
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