Comparison of AxSYM and Architect i1000 sr system for determination of digoxin concentration

Abstract：Objective: To assess the correlation between the serum digoxin levels measured by AxSYM and Architect i1000 sr systems and compare the two systems with respect to interference from digoxin-like immunoreactive substances.Methods:Serum digoxin levels of 100 patients were determined by AxSYM and Architect i1000 sr systems. Regression analysis was performed to evaluate the correlation. The interference of digoxin-like immunoreactive substances on both assays was investigated in samples from 56 patients who were not taking digoxin.Results:Serum digoxin levels determined by Architect i1000 sr system were signiifcantly lower than those of AxSYM system. Concordance analysis revealed a positive and statistically signiifcant correlation coefifcient (r = 0.931). The equation wasY = 0.746X– 0.315 8. The apparent digoxin concentrations were 0 in all of the non digoxin-treated patients when measured with Architect i1000 sr system, while the apparent digoxin concentrations of 28 non digoxin-treated patients were greater than 0.3 ng·mL-1 when measured with AxSYM system.Conclusion:The correlation between the serum digoxin levels from both assays is well. However, values obtained by Architect i1000 sr system are lower than those of AxSYM system. Susceptibility to interference from digoxin-like immunoreactive substances of AxSYM system was signiifcantly greater than that of Architect i1000 sr system.