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Multicenter Analytical Validation of Aβ40 Immunoassays.
Linda J C van Waalwijk van Doorn1,2, Luka Kulic3, Marleen J A Koel-Simmelink4
1Department of Neurology, Radboud University Medical Center, Radboud Alzheimer Centre, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, Netherlands.
Frontiers in Neurology
|July 21, 2017
Summary
Six cerebrospinal fluid (CSF) amyloid-beta 40 (Aβ40) assays were analytically validated. While generally performing well, some recovery and parallelism issues were noted, leading to an improved standard operating procedure (SOP) for assay implementation.
Area of Science:
- Biomarker Assay Validation
- Clinical Chemistry
- Neurodegenerative Disease Diagnostics
Background:
- Analytical validation is crucial for clinical implementation of biomarker assays.
- Amyloid-beta 42/40 (Aβ42/Aβ40) ratio is of significant interest for routine diagnostics.
- This study focuses on validating Aβ40 assays in cerebrospinal fluid (CSF).
Purpose of the Study:
- To compare the analytical performance of six Aβ40 assays.
- To validate these assays in multiple laboratories using a standardized operating procedure (SOP).
- To evaluate and refine the SOP for ELISA assay implementation.
Main Methods:
- Six Aβ40 assays from different vendors were validated across multiple centers.
- Validation followed international consensus protocols, assessing sensitivity, precision, linearity, recovery, and parallelism.
- Inter-laboratory variation was determined using 20 CSF samples.
Main Results:
- Most assays met predefined performance criteria across laboratories.
- Out-of-range recovery and parallelism results were observed in some instances.
- Dilutional linearity and hook-effect experiments were not consistently executed; inter-laboratory variation was low.
- Absolute Aβ40 concentrations varied up to 4.7-fold between extreme assays.
Conclusions:
- Validated Aβ40 assays demonstrated good technical quality and general performance.
- Findings led to the development of a revised validation SOP.
- The improved SOP aims to streamline the implementation of novel immunoassays in clinical practice.
