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Accuracy, precision, and consistency of methods for pathogen-specific cerebrospinal fluid/serum Q-value calculation
Andreas Osterman1, Stephan Böhm1, Peter Osterman2
1Max von Pettenkofer-Institute, Virology, National Reference Center for Retroviruses, Faculty of Medicine, LMU München, Munich, Germany; German Center for Infection Research (DZIF), Partner Site Munich, Munich, Germany.
Journal of Immunological Methods
|November 4, 2019
Summary
Six methods for determining Q-values from optical density (OD) measurements were evaluated for accuracy and precision. Parameter variation methods proved more reliable than selection rule applications for Q-value determination in CSF/serum antibody index analysis.
Area of Science:
- Clinical Chemistry and Diagnostics
- Immunology
- Biostatistics
Background:
- The Q-value, a ratio of antibody concentrations in cerebrospinal fluid (CSF) and serum, is crucial for determining the pathogen-specific antibody index.
- Accurate Q-value determination relies on optical density (OD) measurements and appropriate evaluation methods, impacting diagnostic reliability.
Purpose of the Study:
- To assess the accuracy, precision, and parameter consistency of six different Q-value determination methods.
- To compare methods based on the Four Parameters Logistic (4PL) equation, the α-method, and polygonal line calibration.
- To evaluate the impact of parameter variation versus selection rules on Q-value reliability.
Main Methods:
- Evaluation of six Q-value determination methods using OD data from 51 CSF/serum sample pairs from proficiency surveys (MRZH reaction).
- Methods included Four Parameters Logistic (4PL) equation, α-method, and polygonal line approaches, with variations in OD data points (two vs. four).
- Assessment of accuracy, precision, and parameter consistency, including statistical comparison between 4PL and α-method evaluations.
Main Results:
- All assessed methods demonstrated comparable accuracy and precision in Q-value determination.
- Standard curve methods showed no significant difference in evaluation using two or four ODs.
- Parameter consistency was identified as a key factor influencing accuracy and precision, with statistically significant differences observed between 4PL and α-method evaluations.
Conclusions:
- Q-values derived from parameter variation methods are generally more reliable than those obtained through selection rule applications.
- Parameter consistency is critical for the accuracy and precision of standard curve methods in Q-value determination.
- The study highlights the importance of robust evaluation methods for accurate antibody index assessment in clinical diagnostics.
