COMPARISON OF 3 COMMERCIAL PSA ASSAYS - RESULTS OF RESTANDARDIZATION OF THE CIBA-CORNING METHOD

BACKGROUND. Consistency in prostate-specific antigen (PSA) quantitatio n by different PSA test manufacturers would minimize potential clinica l confusion. The Ciba Coming ACS(TM) PSA(2) calibration has been adjus ted 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 w ith the IMx (Abbott Laboratories) and Tandem R (Hybritech) assays. MET HODS. Archival serum was used that had been stored at -70 degrees C fr om 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; 4 4 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 ve rsus 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 slo pes 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 da ta demonstrate substantial equivalence of the restandardized ACS assay and of the Hybritech method. Significant bias exists between these me thods and the IMx assay with lower results being identified with the l atter. These findings have significant implication, particularly in sc reening when results of an IMx assay are compared to other assays. (C) 1997 Wiley-Liss, Inc.