title: Analytical performance of the VITROS® Immunodiagnostic Products total PSA II and free PSA assays.
abstract: OBJECTIVE
  To assess the precision and the performance of the VITROS(®) total PSA II (tPSA) and free PSA (fPSA) assays on the VITROS(®) ECi/ECiQ Immunodiagnostic system.
  
  
  METHODS
  The precision of the tPSA and fPSA assays was evaluated following the Clinical and Laboratory Standards Institute (CLSI)-guideline EP5-A2. During a 20-day period, 2 runs of 5 quality control (QC) samples were performed daily. Results of tPSA (n=292) and fPSA (n=289) were compared between VITROS(®) ECi/ECiQ Immunodiagnostic system and Roche Cobas 8000 e602 system (Cobas tPSA and fPSA assays). A modified CLSI-guideline EP9-A2 was used to correlate the results based on a Deming regression correlation study.
  
  
  RESULTS
  A within-run and within-calibration imprecision of ≤2% was obtained for all 5 QC concentration levels for both tPSA and fPSA. Method comparison revealed a constant bias of 17% for tPSA and 6% for fPSA. These values are within the desirable bias of 18.7% suggested by the Westgard Biological Variation Database Specifications. A high agreement was found between the two methods, with correlation coefficients of 0.997 and 0.993 for tPSA and fPSA respectively.
  
  
  CONCLUSIONS
  The VITROS(®) tPSA and fPSA assays showed an excellent precision and bias and a good correlation with the Roche method.
authors.affiliation: Department Clinical Chemistry, ZNA Hospitals, Antwerp, Belgium. Electronic address: stevendekeukeleire@hotmail.com.
authors.forename: Steven
authors.initials: S
authors.lastname: De Keukeleire
authors.affiliation: Department Clinical Chemistry, ZNA Hospitals, Antwerp, Belgium.
authors.forename: Annick
authors.initials: A
authors.lastname: Wauters
authors.affiliation: Department Clinical Chemistry, ZNA Hospitals, Antwerp, Belgium.
authors.forename: Dave
authors.initials: D
authors.lastname: Luyts
authors.affiliation: Ortho Clinical Diagnostics, Buckinghamshire, UK.
authors.forename: Candice
authors.initials: C
authors.lastname: Chandler
authors.affiliation: Department Clinical Chemistry, ZNA Hospitals, Antwerp, Belgium.
authors.forename: Marian
authors.initials: M
authors.lastname: Piqueur
mesh_terms: D002138:Calibration; D006801:Humans; D007159:Immunologic Tests / Q000379:methods* / Q000592:standards*; D008297:Male; D017430:Prostate-Specific Antigen / Q000737:chemistry*
chemical_list: D017430:Prostate-Specific Antigen
keywords: Analytical performance; Method comparison; PSA; Prostate specific antigen; fPSA; tPSA