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

Area of Science:

• Clinical Chemistry
• Hematology
• Diagnostic Assays

Background:

• A novel one-stage factor VIII (FVIII) assay from Roche Diagnostics was developed for quantitative assessment of FVIII activity.
• The analytical performance of this FVIII assay was evaluated on the cobas t 711 automated analyzer.

Purpose of the Study:

• To evaluate the analytical performance of a new one-stage FVIII assay.
• To assess the assay's precision, reproducibility, lot-to-lot variability, and correlation with a comparator method.
• To establish the assay-specific reference range for FVIII activity.

Main Methods:

• Multicenter evaluation across three laboratories using citrated plasma samples.
• Determination of assay precision (within-run, within-laboratory) and total reproducibility using plasma pools and controls.
• Method comparison using Passing-Bablok and Deming regression against a Sysmex CS-5100 analyzer.
• Determination of lot-to-lot variability and assay-specific reference range.

Main Results:

• Excellent precision with coefficients of variation (CVs) ranging from 0.9% to 3.8% for samples with >1.0 IU/dL FVIII activity.
• Good intermediate precision (CV 1.8%-4.7%) and total reproducibility (CV 2.0%-13.3%) observed across a wide range of FVIII activity levels.
• Excellent lot-to-lot variability (Pearson's r = .999) and strong correlation with the comparator assay (Pearson's r = .993-.996).
• Established reference range for FVIII activity: 82.2-218.0 IU/dL.

Conclusions:

• The one-stage FVIII assay demonstrates robust analytical performance on the cobas t 711 analyzer.
• The assay's precision, reproducibility, and correlation support its reliability for clinical use.
• The findings support the assay's suitability for routine laboratory practice in quantifying FVIII activity.