Comparison of three commercial PSA assays: results of restandardization of the Ciba Corning method.
BACKGROUND
Consistency in prostate-specific antigen (PSA) quantitation by different PSA test manufacturers would minimize potential clinical confusion. The Ciba Corning ACS PSA2 calibration has been adjusted for alignment with a proposed international standard and clinical concordance with the Hybritech Tandem R assay. Herein we evaluate the clinical effectiveness of this recalibrated PSA test by comparing it with the IMx (Abbott Laboratories) and Tandem R (Hybritech) assays.


METHODS
Archival serum was used that had been stored at -70 degrees C from men who underwent ultrasound-guided prostate needle biopsy. Assays were run according to each manufacturer's specifications in singlicate on a single thaw.


RESULTS
The study included sera of 191 patients; 44 of the patients had carcinoma. There were 151 men with PSA (Tandem R) in the range of 0-10.0 ng/ml, 28 of whom had cancer. The correlation coefficients for Tandem R versus ACS, Tandem R versus IMx, and ACS versus IMx were 0.958, 0.955, 0.979 for benign patients and 0.960, 0.954, and 0.985 for those with cancer, respectively. The corresponding slopes were 1.029, 0.855, and 0.824 for men without and 1.044, 0.830, and 0.790, respectively, for those with malignancy.


CONCLUSIONS
These data demonstrate substantial equivalence of the restandardized ACS assay and of the Hybritech method. Significant bias exists between these methods and the IMx assay with lower results being identified with the latter. These findings have significant implication, particularly in screening when results of an IMx assay are compared to other assays.
Brawer
M K
MK
Department of Urology, University of Washington, Seattle, USA.
Bankson
D D
DD
Haver
V M
VM
Petteway
J C
JC
D005069:Evaluation Studies as Topic; D006801:Humans; D008297:Male; D008722:Methods; D017430:Prostate-Specific Antigen / Q000032:analysis*; D012015:Reference Standards
D017430:Prostate-Specific Antigen