Evaluation of the COBAS CORE Immunoassay for measuring prostate-specific antigen (PSA)--multi-centre study results....

Hoffmann-La Roche has introduced a fully automated COBAS CORE EIA for the measurement of prostate specific antigen (PSA). A regular and an ultrasensitive version of the assay are available. Both versions of the COBAS CORE PSA EIA were compared with the established IMx PSA assay from Abbott. Sera from 98 apparently healthy males, 224 patients with benign prostate hyperplasia, 17 patients with prostatitis and 111 patients with prostate cancer were determined using the COBAS CORE PSA EIA in comparison with the IMx PSA assay. The sera were drawn before treatment. Sera from 26 patients were also monitored through follow-up testing. The COBAS CORE analyser allows rapid analysis of large series of samples. Intra-assay imprecision (CV) was between 1.7% and 4.9% (IMx PSA: between 2.4% and 2.7%). The coefficient of variation for inter-assay imprecision was between 3.4% and 6.5% (IMx PSA: between 3.2% and 3.3%). The analytical detection limit was determined as 0.2 microgram/l for the regular COBAS CORE PSA EIA and 0.05 microgram/l for the ultrasensitive version. A biological detection limit of 0.1 microgram/l was determined for the ultrasensitive version. Results obtained using the COBAS CORE PSA EIA and IMx PSA assays were in excellent correlation: coefficient of correlation r = 0.99 and slope = 0.92, using prostate-specific antigen values from the complete study. Only in the measuring range below 10 micrograms/l did the coefficients of correlation vary between 0.82 and 0.93.(ABSTRACT TRUNCATED AT 250 WORDS)