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Reliability analysis of first and second generation PSA assays
L F Wymenga1, K Groenier, P Visser-van Brummen
1Department of Urology, Martini Hospital, NL-9700 RM Groningen, The Netherlands.
Purpose:
To assess the reliability of first and second generation PSA assays.
Materials And Methods:
In the present investigation we sought to compare pretreatment serum PSA levels determined by a first (IMx) and a second (IMMULITE) generation PSA assays to determine whether there were differences. Sera from 545 men were investigated in the range > 0 - 5330 microg/L, and prostatic histology was known, based on either transrectal ultrasound (TRUS), guided systematic needle biopsies, or transurethral resection or prostatectomy.
Results:
Over the entire range there was an excellent correlation (r > 0.97) between the IMx and the IMMULITE PSA assays. When analyzed according to histology, there was an equivalent slope in the PSA ranges for patients with benign prostatic hyperplasia compared with prostate cancer patients. The area under the ROC curve for the IMx for the total PSA range was 0.7860, and for the IMMULITE assay the area under the ROC curve was 0.7810, a striking resemblance and not different significantly (p=0.87).
Conclusion:
For the majority of men, the first (IMx) and second (IMMULITE) generation PSA assays are equivalent. Small differences between both assays will not be of clinical significance for most men, but should be considered when comparing results of different assays in sequential determinations for a specific man.