Abstract Number: PB0366
Meeting: ISTH 2021 Congress
Background: Factor XII (FXII) initiates the intrinsic coagulation pathway. FXII deficiency is mostly asymptomatic; thus, discovery is usually by detection of a prolonged activated partial thromboplastin time (aPTT). We performed a multicenter evaluation of a one-stage clotting assay in combination with aPTT for the quantitative determination of FXII activity.
Aims: Evaluate the analytical performance of the FXII assay on the high throughput cobas t 711 analyzer (Roche Diagnostics International Ltd, Rotkreuz, Switzerland).
Methods: Performance evaluation at sites in Freiburg, Sheffield, and Vienna (September 2020–February 2021) used 3.2% citrated, anonymized, ethically approved, residual routine or commercially purchased plasma samples. Five human plasma pools and two controls were used for determination of assay repeatability (one run/site; n=21 replicates/sample), intermediate precision, and total reproducibility (five aliquots/sample/day for five days) and coefficients of variation (CVs) were calculated. Lot-to-lot variability (three reagent lots) and method comparison (versus Siemens Coagulation FXII Deficient Plasma [with Dade Actin FS] on Sysmex CS-5100 analyzer), using three sets of ≥120 samples covering the assay measuring range, were evaluated by Passing-Bablok and Deming regression, respectively, and Pearson’s r calculated. The reference range was determined with three different reagent lots (Freiburg only) using fresh plasma samples from 199 healthy individuals aged ≥18 years, not receiving anticoagulants.
Results: Repeatability for the FXII assay across all sites was excellent (CV, 0.8–3.2%). High intermediate precision (CV, 1.5–5.1%) and good total reproducibility (CV, 3.5–4.3%) were demonstrated. The FXII assay showed excellent lot-to-lot variability (Pearson’s r, 0.997–0.998; Table 1) and good agreement with the comparator assay (Pearson’s r, 0.967–0.989; Table 2). Among healthy individuals, 2.5th and 97.5th percentiles for FXII activity were: 52.7 IU/dL and 169.0 IU/dL.
|Lot||A vs B||C vs A||B vs C|
|Relative mean bias at 20 IU/dL, %||-0.4||1.5||5.4|
|Relative mean bias at 70 IU/dL, %||-0.7||1.3||3.4|
|Relative mean bias at 20 IU/dL, %||15.0||3.9||5.0|
|Relative mean bias at 70 IU/dL, %||11.5||-0.6||3.3|
Conclusions: The robust analytical performance of the FXII assay on the cobas t 711 analyzer supports its use in the routine clinical laboratory setting.
To cite this abstract in AMA style:Büchsel M, Creaghan J, Geisen U, Jilma P, Jones R, Kitchen S, Rozsnyai G, Quehenberger P. Multicenter Performance Evaluation and Reference Ranges for the Quantitative Determination of Factor XII Activity by One-stage Factor Assay on the Cobas t 711 Analyzer [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/multicenter-performance-evaluation-and-reference-ranges-for-the-quantitative-determination-of-factor-xii-activity-by-one-stage-factor-assay-on-the-cobas-t-711-analyzer/. Accessed December 6, 2023.
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