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Evaluation of nine automated high-sensitivity C-reactive protein methods: implications for clinical and
W L Roberts1, L Moulton, T C Law
1Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA. william.robert@arup-lab.com
Insights
High-sensitivity C-reactive protein (hs-CRP) assays are crucial for predicting coronary events. Four of nine evaluated hs-CRP methods showed similar results in healthy individuals, but standardization is still needed for clinical interpretation.
Area of Science:
- Clinical Chemistry
- Cardiovascular Disease Biomarkers
- Assay Development and Validation
Background:
- C-reactive protein (CRP) offers prognostic value for future coronary events in healthy individuals.
- Accurate risk assessment necessitates high-sensitivity CRP (hs-CRP) assays beyond traditional clinical laboratory capabilities.
Purpose of the Study:
- To evaluate the performance of nine commercially available high-sensitivity C-reactive protein (hs-CRP) assays.
- To assess assay characteristics including limit of detection, linearity, precision, and prozone effect.
- To compare hs-CRP results across methods using samples from apparently healthy individuals.
Main Methods:
- Evaluation of nine hs-CRP methods (Dade Behring, Daiichi, Denka Seiken, Diagnostic Products Corporation, Iatron, Kamiya, Olympus, Roche, Wako).
- Assessed parameters: limit of detection, linearity, precision (CVs), prozone effect, and method comparability.
- Analyzed samples from 388 apparently healthy individuals.
Main Results:
- Most methods met or exceeded claimed quantification limits, with exceptions noted (Kamiya, Roche, Wako).
- All methods demonstrated linearity between 0.3-10 mg/L; imprecision (CVs >10%) observed at 0.15 mg/L for specific methods (DPC, Kamiya, Olympus, Wako).
- Method-dependent variations in hs-CRP quartiles were observed in healthy populations, though most subjects (68-95%) fell within one quartile of the comparison method.
Conclusions:
- Four of nine hs-CRP methods demonstrated comparable quartile classifications to the reference method in apparently healthy subjects.
- Method-dependent variability in hs-CRP results highlights the need for further standardization.
- Standardization is essential for consistent interpretation of hs-CRP results using population-based cutpoints.
Background:
C-Reactive protein (CRP) can provide prognostic information about risk of future coronary events in apparently healthy subjects. This application requires higher sensitivity assays than have traditionally been available in the clinical laboratory.
Methods:
Nine high-sensitivity CRP (hs-CRP) methods from Dade Behring, Daiichi, Denka Seiken, Diagnostic Products Corporation, Iatron, Kamiya, Olympus, Roche, and Wako were evaluated for limit of detection, linearity, precision, prozone effect, and comparability with samples from 388 apparently healthy individuals.
Results:
All methods had limits of detection that were lower than the manufacturers' claimed limit of quantification except for the Kamiya, Roche, and Wako methods. All methods were linear at 0.3-10 mg/L. The Diagnostic Products Corporation, Kamiya, Olympus, and Wako methods had imprecision (CVs) >10% at 0.15 mg/L. The Iatron, Olympus, and Wako methods demonstrated prozone effects at hs-CRP concentrations of 12, 206, and 117 mg/L, respectively. hs-CRP concentrations demarcating each quartile in a healthy population were method-dependent. Ninety-two to 95% of subjects were classified into the same quartile of hs-CRP established by the Dade Behring method by the Denka Seiken, Diagnostic Products Corporation, Iatron, and Wako methods. In contrast, 68-77% of subjects were classified into the same quartile by the Daiichi, Kamiya, Olympus, and Roche methods. No subject varied by more than one quartile by any method.
Conclusions:
Four of the nine examined hs-CRP methods classified apparently healthy subjects into quartiles of hs-CRP similar to the classifications assigned by the comparison method. Additional standardization efforts are required because an individual patient's results will be interpreted using population-based cutpoints.