title: Challenges in harmonizing integrated healthcare network laboratories: multi-center evaluation of the hCG5 assay.
abstract: BACKGROUND
  Beckman Coulter recently introduced a new hCG assay manufactured for the Access 2 and DxI platforms. This assay is the first to use the 5th International Standard (5th IS) as its primary calibration material. Clinical laboratories are required to validate the method performance before testing and reporting patient results.
  
  
  METHODS
  Beckman Coulter Access 2 instruments (n=41) across Kaiser Permanente Northern California were evaluated for their performance characteristics using the hCG5 reagent. Precision, linearity, dilution verification, and patient sample comparisons were performed on each instrument.
  
  
  RESULTS
  The assay was linear up to 1350IU/L. Intra-day and inter-day precision ranged from 1.0%-3.3% and 1.8-7.3%, respectively, for the low QC material (mean concentration 4.6IU/L). Percent bias between the previous assay (hCG2) and the hCG5 assay was 3.2 to 22.7% for hCG concentrations <1000IU/L and -2.9 to 30% for concentrations >1000IU/L. On board and manual dilutions agreed within 15% following proper adjustment of the instrument dilution factor.
  
  
  CONCLUSIONS
  Achieving Access 2 inter-instrument agreement on specimens needing dilutions (hCG>1350IU/L) requires validation of the on board dilution factor. Laboratories should use QC material above the linear range to monitor instrument dilution accuracy and precision.
authors: Kaiser Permanente, TPMG Northern California Regional Laboratory, Berkeley, CA, United States. Electronic address: dngreene@uw.edu.
authors: Dina N
authors: DN
authors: Greene
authors: University of Washington, Department of Laboratory Medicine and Pathology, Seattle, WA, United States.
authors: Geoffrey S
authors: GS
authors: Baird
authors: Kaiser Permanente, TPMG Northern California Regional Laboratory, Berkeley, CA, United States.
authors: Shiu-Land
authors: SL
authors: Kwong
authors: Kaiser Permanente, TPMG Northern California Regional Laboratory, Berkeley, CA, United States.
authors: Thomas S
authors: TS
authors: Lorey
authors: University of British Columbia, Department of Pathology and Laboratory Medicine, Vancouver, BC, Canada.
authors: Daniel T
authors: DT
authors: Holmes
mesh_terms: D001769:Blood; D002138:Calibration; D019963:Clinical Chemistry Tests; D019033:Delivery of Health Care, Integrated / Q000458:organization & administration*; D006801:Humans; D007201:Indicator Dilution Techniques; D007202:Indicators and Reagents / Q000032:analysis*; D007753:Laboratories / Q000458:organization & administration*; D011786:Quality Control; D015203:Reproducibility of Results
chemical_list: D007202:Indicators and Reagents
keywords: 5th IS; Access 2; Beckman Coulter; Dilution; Harmonization; Validation; hCG