title: A comparison between two different automated total 25-hydroxyvitamin D immunoassay methods using liquid chromatography-tandem mass spectrometry.
abstract: BACKGROUND
  Total 25-hydroxyvitamin D [25(OH)D] is the most reliable indicator of vitamin D status. In this study, we compared two automated immunoassay methods, the Abbott Architect 25-OH Vitamin D assay and the Roche Cobas Vitamin D total assay, with the liquid chromatography-tandem mass spectrometry (LC-MS/MS).
  
  
  METHODS
  One hundred venous blood samples were randomly selected from routine vitamin D tests. Two of the serum aliquots were analyzed at the Abbott Architect i2000 and the Roche Cobas 6000's module e601 in our laboratory within the same day. The other serum aliquots were analyzed at the LC-MS/MS in different laboratory. Passing-Bablok regression analysis and Bland-Altman plot were used to compare methods. Inter-rater agreement was analyzed using kappa (κ) analysis.
  
  
  RESULTS
  The Roche assay showed acceptable agreement with the LC-MS/MS based on Passing-Bablok analysis (intercept: -5.23 nmol/L, 95% CI: -8.73 to 0.19; slope: 0.97, 95% CI: 0.77 to 1.15). The Abbott assay showed proportional (slope: 0.77, 95% CI: 0.67 to 0.85) and constant differences (intercept: 17.08 nmol/L; 95% CI: 12.98 to 21.39). A mean bias of 15.1% was observed for the Abbott and a mean bias of -14.1% was observed for the Roche based on the Bland-Altman plots. We found strong to nearly perfect agreement in vitamin D status between the immunoassays and LC-MS/MS. (κ: 0.83 for Abbott, κ: 0.93 for Roche) using kappa analysis.
  
  
  CONCLUSIONS
  Both immunoassays demonstrated acceptable performance, but the Roche Cobas assay demonstrated better performance than the Abbott Architect in the studied samples.
authors.affiliation: Dumlupinar University, Faculty of Medicine, Department of Medical Biochemistry, Kutahya, Turkey.
authors.forename: Fatma Emel
authors.initials: FE
authors.lastname: Kocak
authors.affiliation: Selcuk University, Faculty of Medicine, Department of Medical Biochemistry, Konya, Turkey.
authors.forename: Bahadir
authors.initials: B
authors.lastname: Ozturk
authors.affiliation: Dumlupinar University, Evliya Celebi Education and Research Hospital, Department of Medical Biochemistry, Kutahya, Turkey.
authors.forename: Ozben Ozden
authors.initials: OO
authors.lastname: Isiklar
authors.affiliation: Dumlupinar University, Faculty of Medicine, Department of Medical Microbiology, Kutahya, Turkey.
authors.forename: Ozlem
authors.initials: O
authors.lastname: Genc
authors.affiliation: Selcuk University, Faculty of Medicine, Department of Medical Biochemistry, Konya, Turkey.
authors.forename: Ali
authors.initials: A
authors.lastname: Unlu
authors.affiliation: Dumlupinar University, Faculty of Medicine, Department of Medical Biochemistry, Kutahya, Turkey.
authors.forename: Irfan
authors.initials: I
authors.lastname: Altuntas
mesh_terms: D016477:Artifacts; D002853:Chromatography, Liquid / Q000379:methods; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation* / Q000379:methods; D008297:Male; D015588:Observer Variation; D011485:Protein Binding; D011897:Random Allocation; D015203:Reproducibility of Results; D012494:Sampling Studies; D053719:Tandem Mass Spectrometry / Q000379:methods; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000175:diagnosis; D014809:Vitamin D-Binding Protein / Q000737:chemistry
chemical_list: D014809:Vitamin D-Binding Protein; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: 25-Hydroxyvitamin D; chromatography; immunoassay; methods; tandem mass spectrometry