Brawer M K, Daum P, Petteway J C, Wener M H
Department of Urology, University of Washington, Seattle 98108, USA.
Prostate. 1995 Jul;27(1):1-6. doi: 10.1002/pros.2990270102.
Consistency and reproducibility of serum prostate-specific antigen (PSA) measurement are essential in the application of this analyte to early detection or screening programs. In the present investigation, we sought to compare serum PSA levels determined by the IMx assay (Abbott Laboratories, North Chicago, IL) and the Tandem E (Hybritech Inc., San Diego, CA) to determine whether there were differences. Two hundred twenty-eight random sera from our archival bank were investigated. One hundred-eight specimens were in the Tandem range of 2.0-10.0 ng/ml, and prostatic histology was known based on either systematic sector needle biopsy or transurethral resection. PSA was measured with three different lost of the IMx and Tandem assays. Over the entire range, there was a good correlation (r2 = 0.985); however, in the more useful clinical range of 2.0-10.0 ng/ml, the correlation was reduced to 0.923; in the 2.0-6.0 ng/ml range, it was further reduced to 0.852. The slope for the entire range was 0.948; however, in the 2.0- to 10.0-ng/ml range, it was 0.894; in the 2.0- to 6.0-ng/ml range, the slope was 0.815. Using PSA cutoffs of 4.0, 5.0, and 6.0 ng/ml, significant decrease in abnormal PSA values in men with cancer was observed with the IMx compared with Tandem. These data suggest that the IMx and the Tandem PSA assays are not equivalent, and in most patients a lower value is realized with the IMx assay. This bias appears to be greater in men with prostate cancer. Clinicians must be aware which assay their patients are being tested with, and laboratory technicians should run internal standards to ensure lack of significant intralot variability and consistency over time.
血清前列腺特异性抗原（PSA）检测结果的一致性和可重复性对于将该分析物应用于早期检测或筛查项目至关重要。在本研究中，我们试图比较由IMx检测法（雅培实验室，伊利诺伊州北芝加哥）和Tandem E检测法（Hybritech公司，加利福尼亚州圣地亚哥）测定的血清PSA水平，以确定两者是否存在差异。我们对存档库中的228份随机血清进行了研究。108份标本的Tandem检测值在2.0 - 10.0 ng/ml范围内，并且基于系统扇形针吸活检或经尿道切除术可知前列腺组织学情况。使用IMx和Tandem检测法的三种不同批次对PSA进行检测。在整个范围内，两者具有良好的相关性（r2 = 0.985）；然而，在更具临床意义的2.0 - 10.0 ng/ml范围内，相关性降至0.923；在2.0 - 6.0 ng/ml范围内，进一步降至0.852。整个范围的斜率为0.948；然而，在2.0至10.0 ng/ml范围内，斜率为0.894；在2.0至6.0 ng/ml范围内，斜率为0.815。使用4.0、5.0和6.0 ng/ml的PSA临界值时，与Tandem检测法相比，IMx检测法观察到癌症男性患者中异常PSA值显著降低。这些数据表明IMx和Tandem PSA检测法并不等效，并且在大多数患者中，IMx检测法得出的值更低。这种偏差在前列腺癌男性患者中似乎更大。临床医生必须清楚其患者接受的是哪种检测法，并且实验室技术人员应运行内部标准以确保批内无显著变异性且随时间保持一致性。
