Comparing the digoxin test with the Architect® i1000sr system with respect to the AxSYM® system

Area of Science:

• Clinical Chemistry
• Immunoassay Technology
• Therapeutic Drug Monitoring

Background:

• Digoxin is a critical medication requiring precise therapeutic drug monitoring.
• Existing assays like the Digoxin II on AsSYM® provide a benchmark for digoxin level determination.
• Newer automated analyzers require validation against established methods.

Purpose of the Study:

• To evaluate the performance of the Architect® i1000sr analyzer for serum digoxin determination.
• To compare the Architect® digoxin assay against the established AsSYM® Digoxin II assay.
• To assess the clinical utility of the Architect® system for digoxin monitoring.

Main Methods:

• Prospective analysis of 100 patient serum samples undergoing digoxin therapy.
• Simultaneous processing of samples on both AxSYM® and Architect® platforms.
• Statistical assessment using linear regression, coefficient of determination, mean absolute error, mean squared prediction error, and Bland-Altman analysis.

Main Results:

• A high correlation coefficient (0.93) was observed between the two systems.
• Significant discrepancies noted: nearly 40% difference between 0.8-2 ng/ml and 20% in other ranges.
• The Architect® system demonstrated high precision in its measurements.

Conclusions:

• The Architect® system exhibits high precision for digoxin measurement.
• However, the system's accuracy is clinically unacceptable for patient monitoring when compared to the AxSYM® assay.
• Discrepancies may affect therapeutic drug management decisions.