Abbott IMx evaluated for assay of prostate-specific antigen in serum

We evaluated a new fully automated procedure for quantitative measurement of prostate-specific antigen (PSA) by the Microparticle Enzyme Immunoassay (MEIA) technology developed for the Abbott IMx automated immunoassay system. The performance characteristics of the Abbott IMx PSA assay (y) were evaluated and compared with those of the Hybritech Tandem-E PSA assay (x), a solid-phase two-site immunoenzymometric assay. PSA values for both assays were well correlated (r = 0.99); regression analysis yielded the equation y = 0.92x - 0.23 micrograms/L. The Abbott assay proved reliable and reproducible, as shown by the intra- and interassay coefficients of variation (2.0-3.4% and 3.1-4.7%, respectively). The assay gave a linear standard curve up to 100 micrograms/L and was very sensitive (detected PSA < 0.1 microgram/L). This analytical sensitivity was comparable with that of the Tandem-E PSA assay. Overall, the IMx PSA assay demonstrated the accuracy, precision, linearity, and intermethod correlation required for monitoring patients with prostate cancer.