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Comparison of different immunoassays for CA 19-9
P Stern1, B Friedecky, V Bartos
1Institute of Clinical Biochemistry, General University Hospital and 1st Faculty of Medicine, Charles University, Prague, Czech Republic. petr.stern@vfn.cz
Clinical Chemistry and Laboratory Medicine
|January 19, 2002
Summary
Different immunoassay kits for cancer antigen 19-9 (CA 19-9) show significant variations. These differences in measurement systems hinder clinical efficacy and necessitate standardization for reliable evidence-based medicine.
Area of Science:
- Clinical Chemistry
- Immunoassay Technology
- Biomarker Analysis
Background:
- Cancer antigen 19-9 (CA 19-9) is a widely used tumor marker.
- Routine clinical use relies on various immunoassay kits with differing analytical systems.
Purpose of the Study:
- To compare the performance of six commonly used immunoassay kits for CA 19-9 measurement.
- To identify systematic and individual differences among these analytical systems.
Main Methods:
- Six immunoassay kits were evaluated using identical clinical and control samples.
- Repeatability (coefficient of variation) was assessed.
- Passing-Bablok regression and Bland-Altman analysis were employed to evaluate systematic and individual differences.
Main Results:
- Repeatability varied from 2.1% to 6.7% across the systems.
- Significant systematic differences were observed among the analytical systems.
- Individual sample differences were more pronounced than systematic variations.
- Cut-off values differed, leading to dissimilar clinical efficacy.
- System behavior with control materials did not always align with biological sample calibration.
Conclusions:
- Results for CA 19-9 are not interchangeable between different analytical techniques, even with identical monoclonal antibodies.
- Standardization of CA 19-9 measurement systems is crucial for reliable clinical decision-making and evidence-based medicine.