title: Evaluation of Beckman Coulter DxI 800 immunoassay system using clinically oriented performance goals.
abstract: OBJECTIVE
  We evaluated the analytical performance of 24 immunoassays using the Beckman Coulter DxI 800 immunoassay systems at Mayo Clinic, Rochester, MN for trueness, precision, detection limits, linearity, and consistency (across instruments and reagent lots).
  
  
  METHODS
  Clinically oriented performance goals were defined using the following methods: trueness-published desirable accuracy limits, precision-published desirable biologic variation; detection limits - 0.1 percentile of patient test values, linearity - 50% of total error, and consistency-percentage test values crossing key decision points. Local data were collected for precision, linearity, and consistency. Data were provided by Beckman Coulter, Inc. for trueness and detection limits.
  
  
  RESULTS
  All evaluated assays except total thyroxine were within the proposed goals for trueness. Most of the assays met the proposed goals for precision (86% of intra-assay results and 75% of inter-assay results). Five assays had more than 15% of the test results below the minimum detection limits. Carcinoembryonic antigen, total thyroxine and free triiodothyronine exceeded the proposed goals of ±6.3%, ±5% and ±5.7% for dilution linearity. All evaluated assays were within the proposed goals for instrument consistency. Lot-to-lot consistency results for cortisol, ferritin and total thyroxine exceeded the proposed goals of 3.3%, 11.4% and 7% at one medical decision level, while vitamin B12 exceeded the proposed goals of 5.2% and 3.8% at two decision levels.
  
  
  CONCLUSIONS
  The Beckman Coulter DxI 800 immunoassay system meets most of these proposed goals, even though these clinically focused performance goals represent relatively stringent limits.
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Neval
authors.initials: N
authors.lastname: Akbas
authors.affiliation: Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA.
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Schryver
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Alicia
authors.initials: A
authors.lastname: Algeciras-Schimnich
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Nikola A
authors.initials: NA
authors.lastname: Baumann
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Darci R
authors.initials: DR
authors.lastname: Block
authors.affiliation: Beckman Coulter, Chaska, MN, USA.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Budd
authors.affiliation: Beckman Coulter, Chaska, MN, USA.
authors.forename: S J Stephen
authors.initials: SJ
authors.lastname: Gaston
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA. Electronic address: klee.george@mayo.edu.
authors.forename: George G
authors.initials: GG
authors.lastname: Klee
mesh_terms: D005293:Ferritins / Q000032:analysis; D007118:Immunoassay / Q000379:methods*; D015203:Reproducibility of Results; D013974:Thyroxine / Q000032:analysis; D014284:Triiodothyronine / Q000032:analysis
chemical_list: D014284:Triiodothyronine; D005293:Ferritins; D013974:Thyroxine
keywords: Analytical performance; Beckman Coulter DxI 800; Immunoassay; Precision; Quality control