Multicenter performance evaluation and reference range determination of a new one-stage factor VIII assay.

INTRODUCTION: We conducted a multicenter evaluation of a new one-stage factor VIII (FVIII) assay (Roche Diagnostics), intended for the quantitative assessment of FVIII activity. We evaluated the analytical performance of the FVIII assay on the cobas t 711 analyzer. METHODS: Experiments performed at three laboratories used 3.2% citrated residual or commercially purchased plasma samples. Five human plasma pools and two controls were used to determine assay within-run and within-laboratory precision, and total reproducibility; coefficients of variation (CVs) and/or standard deviations (SDs) were calculated. Lot-to-lot variability and method comparison (vs Coagulation FVIII Deficient Plasma/Dade Actin FS Activated PTT reagent/Standard Human Plasma Calibrator on the Sysmex CS-5100 analyzer; Siemens Healthineers) were evaluated by Passing-Bablok and Deming regression, respectively, and Pearson's r calculated. Assay-specific reference range was determined using 199 fresh plasma samples from healthy adults, not receiving anticoagulants. RESULTS: Across sites, SDs for repeatability were 0.016-0.046 for samples with ≤1.0 international units (IU)/dL FVIII activity; CVs were 0.9%-3.8% for samples with >1.0 IU/dl activity. Among samples with mean FVIII activity 0.344-133 IU/dl, good intermediate precision (SD 0.020 for samples with 0.344 IU/dl activity; CV 1.8%-4.7%) and good total reproducibility (CV 2.0%-13.3%) were observed. The FVIII assay showed excellent lot-to-lot variability (Pearson's r = .999) and good correlation with the comparator assay (Pearson's r = .993-.996). The reference range for FVIII activity was 82.2-218.0 IU/dl. CONCLUSION: The one-stage FVIII assay demonstrated robust analytical performance on the cobas t 711 analyzer, supporting its use in routine laboratory practice.

System performance evaluation of the cobas t 711 and cobas t 511 coagulation analyzers in routine laboratory settings.

: Utility of coagulation analyzers in real-world settings depends on characteristics that are often not studied comprehensively. This study aimed to investigate the analytical performance, system functionality, practicability, consistency and throughput of two new automated coagulation analyzers in routine laboratory practice. Real-world settings were simulated in three major European hemostasis laboratories and multiple assays were performed in anonymized plasma samples in parallel with routine clinical practice on the cobas t 711 (high-throughput) and cobas t 511 (mid-throughput) analyzers using activated partial thromboplastin time (aPTT), aPTT Lupus, aPTT Screen, Antithrombin (AT), D-Dimer, Fibrinogen, Prothrombin Time (PT)-derived Fibrinogen, PT Owren, PT Rec (recombinant human thromboplastin reagent) and Thrombin Time assays. Precision was tested in a 21-day experiment and accuracy was compared with reference methods of the same laboratory. A number of experiments simulated challenging real-life situations. Pearson's correlation coefficient was more than 0.98 in all assays. Across assays, coefficients of variation ranged from 0.0 to 1.5% for intermediate precision; 0.2 to 3.0% for repeatability and 0.4 to 3.7% for total precision. Good between-run comparability was seen when testing samples under random conditions. Calculated maximum throughput was 197 and 387-402 tests/h for the cobas t 511 and 711 analyzers, respectively. Practicability met or exceeded user expectations in 98% of cases. In a simulated real-life setting of three major laboratories, the new cobas t 511 and cobas t 711 coagulation analyzers demonstrated a good functionality, practicability and performance and the throughput was high.

Evaluating the analytical performance of four new coagulation assays for the measurement of fibrinogen, D-dimer and thrombin time.

INTRODUCTION: New laboratory methods to measure haemostatic function require careful assessment before routine use. We evaluated the analytical performance of four new coagulation assays for the measurement of fibrinogen by Clauss assay, prothrombin time-derived fibrinogen, thrombin time and D-dimer levels. METHODS: The four assays were evaluated on the cobas t 711 and cobas t 511 analysers at four centres in Europe. Analytical performance and method comparisons with other commercially available assays were performed according to Clinical and Laboratory Standards Institute guidelines (EP09-A3, EP05-A3) using residual anonymized human sodium citrate (3.2% [0.109M]) plasma samples. Lot-to-lot variability and the equivalency of each assay on the cobas t 711 and cobas t 511 analysers were also assessed. RESULTS: Overall, coefficients of variance were ≤4.1% and ≤8.6% for within-run precision and total reproducibility, respectively. Method comparison experiments showed good or acceptable agreement for each assay compared with their respective comparator method, and equivalency was demonstrated for the two cobas t platforms (Pearson's correlation coefficient ≥0.991). A high level of consistency was observed between lots for all four assays (Pearson's correlation coefficient ≥0.994). CONCLUSION: This multicentre study demonstrates excellent analytical performance for four new coagulation assays on the cobas t 711 and cobas t 511 analysers.

Evaluating the analytical performance of five new coagulation assays for the measurement of prothrombin time and activated thromboplastin time.

INTRODUCTION: New methods for coagulation tests require careful assessment before routine use. We evaluated the analytical performance of five new coagulation assays for measuring prothrombin time (PT) and activated partial thromboplastin time (aPTT). METHODS: PT Rec, PT Owren, aPTT, aPTT Lupus and aPTT Screen assays (Roche Diagnostics) were evaluated on cobas t 711 and cobas t 511 analysers (Roche Diagnostics) at four European centres. Analytical performance and method comparisons with relevant commercially available assays were performed to Clinical Laboratory Standards Institute guidelines using residual anonymized samples. Lot-to-lot comparison and equivalency of the cobas t analysers were also assessed; reference ranges were determined using samples from apparently healthy volunteers. RESULTS: Overall, coefficients of variation were ≤1.3% for within-run precision and ≤6.3% for total reproducibility across all sites. Deming regression analyses showed good agreement between each assay (cobas t 711) and respective comparator method (Pearson's r: 0.964-0.999, n > 120 samples/assay/site). Passing-Bablok regression analyses demonstrated equivalence of the two cobas t platforms for use with each assay (Pearson's r ≥ 0.995). Lot-to-lot consistency was high for all assays and comparisons (Pearson's r ≥ 0.998). Reference ranges (2.5th-97.5th percentiles; n = 200 samples/assay) in seconds were 8.4-10.6 (PT Rec), 18.2-27.2 (PT Owren), 23.6-30.6 (aPTT), 24.1-31.7 (aPTT Lupus) and 23.9-33.2 (aPTT Screen). CONCLUSION: Based on the excellent analytical performance and good agreement with relevant comparator methods, the five coagulation assays on the novel cobas t 711 and cobas t 511 analysers are suitable for routine use in core laboratories.