title: Analytical issues on prostate-specific antigen in relation to prostate cancer screening.
abstract: OBJECTIVE
  Evaluation of the analytical performance of the Hybritech Tandem-E PSA assay as applied to the Rotterdam part of the European Randomized Study of Screening for Prostate Cancer (ERSPC) during 1994-1997.
  
  
  METHODS
  For assessment of test performance imprecision and accuracy contributing to clinical decision making was examined. Pre-analytical variables (specimen handling), long-term reagents stability and calibration check with the Stanford 90:10 PSA Calibrator were studied.
  
  
  RESULTS
  Total prostate-specific antigen proved to be a stable marker. Provided correct storage at 4 degrees C, we were not able to find differences between samples analyzed directly after blood withdrawal and those analyzed the following day, with or without centrifugation. Day-to-day precision, we found during 1997 a coefficient of variation of 4.9% for concentration 1.8 micrograms/L and 4.2% for 4.8 micrograms/L (n = 182). The variation among the 21 Tandem-E reagent batches used during 1994-1997 proved to be small. Application of the Stanford 90:10 PSA Calibrator revealed 3% higher values for Tandem-E.
  
  
  CONCLUSIONS
  The overall, long-term picture of Tandem-E PSA is reliable in our hands. Possible differences from the true PSA values, not specific for Tandem-E, need to be elaborated.
authors.affiliation: Department of Clinical Chemistry, University Hospital Rotterdam, The Netherlands. blijenberg@ckcl.azr.nl
authors.forename: B G
authors.initials: BG
authors.lastname: Blijenberg
authors.forename: M
authors.initials: M
authors.lastname: Roobol
authors.forename: F H
authors.initials: FH
authors.lastname: Schröder
mesh_terms: D006801:Humans; D007118:Immunoassay / Q000379:methods; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood* / Q000276:immunology; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000401:mortality
chemical_list: D017430:Prostate-Specific Antigen