Abbott Diagnostics

Abstract: Measurements of serum cancer antigen (CA) 15-3 are used to monitor tumor recurrence and treatment of advanced disease We evaluated the performance characteristics, including limit of detection, linearity, method comparison, and reference intervals, of 7 automated methods for CA 15-3, including the Access 2 (Beckman Coulter, Brea, CA), ADVIA Centaur (Bayer Diagnostics, Tarrytown, NY), ARCHITECT i2000 and AxSYM (Abbott Diagnostics, Abbott Park, IL), Elecsys 2010 (Roche Diagnostics, Indianapolis, IN), IMMULITE 2000 (Diagnostic Products, Los Angeles, CA), and VITROS ECi (Ortho Clinical Diagnostics, Raritan, NJ) assays The limit of detection for each assay was less than 10 kU/L The maximum deviation for the target values for linearity samples was less than 10% for all methods Method comparison studies revealed large differences for some individual samples Overall slopes ranged from 050 to 148, and correlation coefficients were 090 to 096 when the ADVIA Centaur was the comparison method The 975 percentile upper reference limit ranged from 233 to 517 kU/L Additional standardization efforts are needed, and the availability of reference material is required Substantial intermethod differences exist for some patient samples, indicating that redetermining the baseline is required when changing methods

Abstract: Elevated concentrations of homocysteine (Hcy) are associated with a range of disorders. Linearity, imprecision, interference, method comparison, and accuracy were evaluated on the ADVIA Centaur (Siemens Healthcare Diagnostics, Deerfield, IL), ARCHITECT i2000SR (Abbott Diagnostics, Abbott Park, IL), AxSYM (Abbott Diagnostics), and IMMULITE 2000 (Siemens Healthcare Diagnostics) methods and analyzers and the Catch (Equal Diagnostics, Exton, PA) and Diazyme (Diazyme Laboratories, San Diego, CA) methods, both on the Modular P analyzer (Roche Diagnostics, Indianapolis, IN). All methods were linear with maximum deviations from target recoveries of less than 10%. Total coefficients of variation ranged from 1.7% to 9.4%. The effects of hemolysis, icterus, and lipemia were assessed. Method comparisons were performed using high-performance liquid chromatography as the comparison method. Correlation coefficients were 0.95 to 0.99. Bland-Altman plots demonstrated percentage bias of -29.3% (IMMULITE) to 7.2% (Centaur). Accuracy using the National Institute of Standards and Technology Standard Reference Material 1955 showed varying results with only 1 method within the certified range for all 3 levels. All methods demonstrated acceptable performance except the IMMULITE, which is less precise and accurate. Standardization of most methods seems acceptable, although continuing efforts are warranted.

Abstract: We have evaluated Roche Diagnostics' RIA-CEA and Abbott Diagnostics' EIA-CEA methods for precision, normal reference interval, concordance, and correlation of malignant disease with increase in carcinoembryonic antigen (CEA) in plasma. In examining concordance, we used data on 138 patients with primary carcinomas of the breast, colon, lung, or pancreas, each further classified by extent of dissemination. We find the two methods to be comparably precise. The respective upper reference limits of normal for the Roche and Abbott methods were determined to be 5.0 micrograms/L and 4.6 micrograms/L. The regression equation for a log transformation of the 177 data points is y = 0.966x + 0.03, where x = Roche and y = Abbott, with a correlation coefficient of 0.948. According to the criteria we used, the concordance was 78.7%. The largest discordance was observed in widely disseminated disease states and in cancers of the colon and pancreas. Paired data analysis of discordance indicated greater increases in apparent CEA by the Abbott method in most colon cancers with liver involvement; six of the eight discordant pancreatic cancers had higher Roche-CEA values. CEA heterogeneity and the role of the liver in CEA metabolism appear to contribute to the observed differences. We show why the two methods should not be used interchangeably, and that baseline values for CEA must be established for each method.