Background: Deficiency of coagulation factors FII, FV and FVII causes prolonged prothrombin time (PT) and bleeding disorders of variable severity depending on factor level activity. We performed a multicentre evaluation of three PT one-stage factor assays for quantitative determination of FII, FV and FVII activity (Roche Diagnostics).

Aims: Evaluate the analytical performances of FII, FV and FVII factor assays on the cobas t 711 analyser.

Methods: Experiments were performed at three laboratories using 3.2% citrated, anonymised, ethically approved, residual/commercially purchased plasma samples. Five human plasma pools (HPPs) and two controls were used for determination of assay repeatability (1 run/site; n=21 replicates per sample), intermediate precision and total reproducibility (5 aliquots/sample per day over 5 days); coefficients of variation (CV) were calculated. Lot-to-lot variability (3 reagent lots) and method comparison (versus Siemens Coagulation FII/FV/FVII Deficient Plasma [with Dade Innovin] on Sysmex CS-5100 analyser), using three sets of ≥120 samples, were evaluated by Passing-Bablok and Deming regression, respectively, and Pearson’s r calculated. Reference ranges were determined (one site) using fresh plasma samples from healthy individuals aged ≥18 years, not receiving anticoagulant medication.

Results: Across sites, CV ranges for repeatability for each assay were: FII, 0.6-3.0%; FV, 0.8-2.5%; FVII, 1.0-1.7%. High intermediate precision (CV: FII, 1.0-2.0%; FV, 1.1-7.0%; FVII, 1.3-3.5%), and good reproducibility (CV: FII, 1.7-2.6%; FV, 2.7-6.1%; FVII, 1.9-3.3%) were shown for each assay. All assays demonstrated excellent lot-to-lot variability (Pearson’s r, 0.998-1.000; Table 1) and high agreement with comparator assays (Pearson’s r, 0.989-0.997; Table 2). Among healthy individuals (n=200), 2.5^th and 97.5^th percentiles for coagulation factor activity were: FII, 78.4-124 IU/dL; FV, 64.0-143 IU/dL; FVII, 56.1-158 IU/dL.

Conclusions: FII, FV and FVII factor assays demonstrated robust analytical performance on the cobas t 711 analyser, supporting use in routine laboratory practice.

[Table 1. Lot-to-lot comparisons for the Roche FII, FV and FVII factor assays]

[Table 2. Method comparisons between the Roche and Siemens FII, FV and FVII factor assays]

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/multicentre-performance-evaluation-and-reference-ranges-for-the-quantitative-determination-of-factors-ii-v-and-vii-by-one-stage-factor-assay-on-the-cobas-t-711-analyser/