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On the standardization of total prostate-specific antigen: an exercise with two reference preparations
B G Blijenberg1, B N Storm, A E Kruger
1Department of Clinical Chemistry, University Hospital Rotterdam, The Netherlands. blijenberg@ckcl.azr.nl
Clinical Chemistry and Laboratory Medicine
|July 27, 1999
Summary
Three prostate-specific antigen assays show high correlation but significant accuracy differences. Recalibration with reference materials did not fully resolve these discrepancies, indicating assays are not interchangeable.
Area of Science:
- Clinical Chemistry
- Biomarker Analysis
- Prostate Cancer Diagnostics
Background:
- Accurate measurement of total prostate-specific antigen (PSA) is crucial for prostate cancer screening and diagnosis.
- Several commercial assays exist, but their interchangeability and accuracy require validation.
Purpose of the Study:
- To compare the performance of three total PSA assays: Tandem R, Tandem E, and Prostatus.
- To evaluate the impact of recalibration using two reference preparations on assay accuracy and agreement.
Main Methods:
- Analysis of 112 serum samples from prostate cancer patients, benign prostatic hyperplasia patients, and a screening cohort.
- Assays used: Tandem R, Tandem E (Hybritech), and Prostatus (Wallac).
- Recalibration performed using Stanford 90:10 PSA Calibrator and CRM 613 Prostate-Specific Antigen.
Main Results:
- High correlations observed between Tandem R, Tandem E, and Prostatus assays.
- Statistically significant differences in accuracy were found between Tandem E and Tandem R, and between Prostatus and Tandem E.
- Recalibration did not resolve these accuracy discrepancies, except for the Tandem R and Tandem E combination.
Conclusions:
- Even after recalibration with reference materials, total PSA assays demonstrate significant differences in accuracy.
- The lack of complete interchangeability among assays necessitates careful consideration in clinical practice and reporting.