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Comparison of two automated nephelometers
K Emancipator1, R J Elin, T A Fleisher
1Clinical Pathology Department, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland.
Journal of Clinical Laboratory Analysis
|January 1, 1992
Summary
Intercalibration of Beckman Array and Behring Nephelometer 100 revealed precision and linearity issues for analytes like apolipoprotein A1 (apo A1) and immunoglobulin G (IgG). Method comparisons showed significant biases, limiting the value of inter-instrumental results for patient care.
Area of Science:
- Clinical Chemistry
- Immunology
- Laboratory Medicine
Background:
- Accurate and reproducible laboratory testing is crucial for clinical diagnosis and patient management.
- Nephelometry is a common method for quantifying proteins in biological samples.
- Intercalibration between different analytical platforms is essential for consistent patient results.
Purpose of the Study:
- To assess the intercalibration precision and linearity of apolipoprotein A1 (apo A1) and immunoglobulin G (IgG) between the Beckman Array and Behring Nephelometer 100 (BN-100).
- To compare analytical methods for 12 different analytes across the two nephelometers.
- To evaluate the clinical utility of comparing results from these two nephelometric platforms.
Main Methods:
- Intercalibration was performed for apo A1 and IgG using the Beckman Array and BN-100.
- Precision and linearity were assessed for these two analytes.
- Method comparison studies were conducted for 12 analytes, including immunoglobulins and proteins, using both instruments.
Main Results:
- Poor precision for IgG was observed with the Beckman Array in two of nine samples, attributed to systematic shifts.
- Statistical non-linearity was noted for apo A1 on the BN-100, though deemed acceptable for clinical diagnosis.
- Method comparisons revealed significant proportional biases (>10%) for seven of 12 analytes and correlation coefficients <0.96 for seven of 12 analytes.
Conclusions:
- The study highlights potential discrepancies in analytical performance between the Beckman Array and BN-100 for specific analytes.
- Significant biases and poor correlations indicate limited value in directly comparing results from these two nephelometers for individual patient assessment.
- Careful validation and consideration of analytical differences are necessary when interpreting patient results across different laboratory platforms.