Long-term analytical performance of apixaban measurements based on external quality assessment data

Area of Science:

• Clinical Chemistry
• Pharmacokinetics
• Laboratory Medicine

Background:

• Direct oral anticoagulants (DOACs) generally do not require routine monitoring.
• Apixaban measurement is increasingly requested in emergency settings and for patients with suspected pharmacokinetic variability.
• Ensuring consistent laboratory results across different platforms is crucial for safe interpretation.

Purpose of the Study:

• To evaluate the long-term analytical performance of apixaban assays.
• To identify sources of analytical variation in apixaban measurements.
• To assess the impact of laboratory platform uniformity on assay performance.

Main Methods:

• Analysis of anonymized external quality assessment (EQA) data from the ECAT program.
• Distribution of lyophilized plasma samples with known apixaban concentrations to participating laboratories.
• Calculation of assay performance metrics including bias, coefficient of variation, and analytical critical difference.

Main Results:

• Apixaban assays demonstrated good long-term precision, with consensus coefficients of variation below 10% above 50 ng/mL.
• Mean total error was 16.8%, primarily driven by random error (10.7%).
• Proportional bias was the main source of deviation, and uniform laboratory platforms showed significantly lower variability.

Conclusions:

• Apixaban assays exhibit robust long-term analytical precision, even with methodological heterogeneity.
• Proportional bias represents the primary source of analytical deviation in apixaban measurements.
• Harmonization of laboratory platforms enhances the reproducibility of apixaban assay results.