Comparison of Three Assays for Total and Free PSA Using Hybritech and WHO Calibrations.

Background/aim: Lack of interchangeability between prostate-specific antigen (PSA) assays could have a clinical impact. We compared PSA assays from different manufacturers and calibrations.

Patients And Methods: A total of 233 men who underwent prostate biopsy (PSA: 2-10 ng/ml; Beckman Coulter Access Hybritech as reference) were enrolled. Total (tPSA) and free PSA (fPSA) were also measured using the Roche cobas and the Abbott Architect methods.

Results: Roche tPSA values were ≈1% higher than Beckman, while Abbott values were ≈5% lower. Roche had the highest diagnostic sensitivity (92%) compared to Beckman Coulter (87%) and Abbott (85%). Roche fPSA was ≈3% lower and Abbott ≈17% higher than that of Beckman. For the percentage of fPSA, Roche had the highest sensitivity (98%).

Conclusion: Roche cobas and Beckman Coulter Access Hybritech tPSA were almost interchangeable. While the agreement was acceptable for tPSA, this did not happen with fPSA and greater efforts for harmonization are required.