title: Method comparison for determination of the tumor markers AFP, CEA, PSA and free PSA between Immulite 2000 XPI and Dimension Vista 1500.
abstract: BACKGROUND
  For the Luminescent Oxygen Channeling Immunoassay (LOCI) technology as established for Dimension Vista 1500, assays have been developed for the serum tumor markers AFP, CEA, PSA and free PSA. We performed a method analysis for these parameters using the Immulite 2000 XPI.
  
  
  METHODS
  Determination of within-day and total imprecision of the methods was carried out according to CLSI guidelines with three serum pools. In addition, parallel measurements were performed with both systems in 1,871 routine serum samples and correlations were calculated.
  
  
  RESULTS
  Calculated total imprecision of the three serum pools for AFP was 3.8 - 4.3%, for CEA 3.3 - 4.3%, for tPSA 3.6 - 4.0% and for fPSA it was 3.5 - 8.2%. Correlations of these markers across the entire value range were very good with the following correlation coefficients: 0.997 for AFP, 0.996 for CEA, 0.971 for tPSA and 0.988 for fPSA. While values for AFP and tPSA from both methods were comparable (slopes 1.02 and 1.01), lower values were measured for CEA and fPSA with the Dimension Vista (slopes 0.83 and 0.91). For AFP, a sample cluster with considerably higher values than with Dimension Vista was observed in the lower measurement range (< 20 ng/mL).
  
  
  CONCLUSIONS
  The assays for AFP, CEA, tPSA and fPSA, as developed with the LOCI technology for the Dimension Vista, show good comparability with results obtained from the Immulite 2000 XPI. However, lower measurement ranges for CEA and fPSA as well as individual divergences, especially with AFP, must be taken into consideration in the event of method changeover.
authors.affiliation: Department of Clinical Chemistry and Clinical Pharmacology, University of Bonn, Bonn, Germany. berndt.zur@ukb.uni-bonn.de
authors.forename: Berndt
authors.initials: B
authors.lastname: Zur
authors.forename: Stefan
authors.initials: S
authors.lastname: Holdenrieder
authors.forename: Gisela
authors.initials: G
authors.lastname: Walgenbach-Brünagel
authors.forename: Eike
authors.initials: E
authors.lastname: Albers
authors.forename: Birgit
authors.initials: B
authors.lastname: Stoffel-Wagner
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D002272:Carcinoembryonic Antigen / Q000097:blood*; D006801:Humans; D007118:Immunoassay / Q000379:methods* / Q000592:standards; D008163:Luminescent Measurements / Q000379:methods* / Q000592:standards; D009369:Neoplasms / Q000097:blood* / Q000175:diagnosis; D017430:Prostate-Specific Antigen / Q000097:blood*; D015203:Reproducibility of Results; D000509:alpha-Fetoproteins / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D002272:Carcinoembryonic Antigen; D000509:alpha-Fetoproteins; D017430:Prostate-Specific Antigen