Evaluation of the Analytical Properties of the Diagon CoagXL Coagulation Analyzer.

BACKGROUND: This study aims to evaluate the analytical properties of the DIAGON CoagXL (Budapest, Hungary) coagulation system. METHODS: The study includes a total of 212 normal, 49 pathologic plasma samples sent to our laboratory. The par-tial thromboplastin time (PTT) and activated partial thromboplastin time (aPTT) measurements were performed on the Diagon CoagXL and Stago StaR coagulometers. The precision, method comparison, carry-over, activity determination, and reference range verification studies were performed with Diagon CoagXL, the test analyzer. RESULTS: In the precision study performed with normal and pathologic plasma samples for the PT and aPTT tests, the within-day coefficient of variation (CV%) was 1.9 in the normal and 0.68 in the pathologic plasma for the PT, and for the aPTT it was 0.61 in the normal and 0.9 in the pathologic plasma. The between-day CV% was 1.6 in the normal plasma and 5.5 in the pathologic plasma for the PT and 3.7 in the normal plasma and 2.1 in the pathologic plasma for the aPTT. In the comparison study, the entire group mean ± standard deviation (mean ± SD) value for the INR was found to be 3.13 ± 1.26 in the CoagXL and 2.67 ± 0.82 in the StaR analyzer. The difference between these values was statistically significant (p < 0.006). For aPTT, mean ± SD value was found to be 39.44 ± 25.02 seconds (sec) in the CoagXL analyzer and 43.4 ± 27.63 sec in the StaR analyzer. The difference between these values was not statistically significant (p > 0.5). In the carryover study, the carryover value was -0.16 for the PT and 0 for the aPTT, which was under the allowable limit value (< 3 SD). In the percent activity determination study, regression equation of prothrombin activity (%) versus time (sec) was found as y = 341.6567 ± 37.1920x + 1.0913x2 (R2 = 0.97). The reference range verification analyses reveal that the manufacturer ranges were acceptable. CONCLUSIONS: Verification studies of CoagXL analyzer system was acceptable. But in comparison studies of PT we saw that there are still problems with recommended INR system.

Evaluation of new Beckman Coulter 25(OH) Vitamin D assay and potential improvement of clinical interpretation.

INTRODUCTION: The aim of this study was to assess the analytical performances of the newly developed Access2 25-hydroxyvitamin D (25(OH)D) total immunoassay on two analysers, DxI800 and Access2 (Beckman Coulter, Brea, CA, USA), and compare these two and a recalibrated Modular E 170 25(OH)D assay (Roche Diagnostics, Penzberg, Germany) with reference liquid chromatography tandem-mass spectrometry (LC-MS/MS) with special emphasis on clinical diagnosis. MATERIALS AND METHODS: Beckman immunoassays were assessed for imprecision, accuracy, limit of blank (LoB), limit of detection (LoD), limit of quantitation (LoQ), linearity, interference, and carryover. One hundred and nineteen samples were run on DxI 800, Access2, and E 170, and agreement with the LC-MS/MS method was evaluated. RESULTS: DxI 800 and Access2 assays showed good performances in terms of LoB, LoD, LoQ, linearity, and interference. All immunoassays showed negative biases ranging from - 8.6% (DxI 800) to - 19.2% (Access2). DxI 800 and Access2 systems had proportional biases, and the E170 system had a constant bias with the largest random error. Concordance correlation coefficient values ranged from 0.941 (CI: 0.917-0.958) for DxI800 to 0.854 (CI: 0.811-0.889) for Access2. Kappa (κ) coefficients were found moderate for Dxl (0.709; CI: 0.581-0.837) and E170 (0.771; CI: 0.587-0.844) and fair for Access2 (0.572; CI: 0.428-0.716). CONCLUSIONS: All immunoassays can be used in routine 25(OH)D measurements, still fairly diagnosing patients' status. Recent standardization attempts seem not to contribute too much to clinical diagnosis. A clinical laboratory must at least be aware of its method to avoid misinterpretation of results.