title: Measurements for 8 common analytes in native sera identify inadequate standardization among 6 routine laboratory assays.
abstract: BACKGROUND
  External quality assessment (EQA) with commutable samples is essential for assessing the quality of assays performed by laboratories, particularly when the emphasis is on their standardization status and interchangeability of results.
  
  
  METHODS
  We used a panel of 20 fresh-frozen single-donation serum samples to assess assays for the measurement of creatinine, glucose, phosphate, uric acid, total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides. The commercial random access platforms included: Abbott Architect, Beckman Coulter AU, Ortho Vitros, Roche Cobas, Siemens Advia, and Thermo Scientific Konelab. The assessment was done at the peer group level and by comparison against the all-method trimmed mean or reference method values, where available. The considered quality indicators were intraassay imprecision, combined imprecision (including sample-matrix interference), bias, and total error. Fail/pass decisions were based on limits reflecting state-of-the-art performance, but also limits related to biological variation.
  
  
  RESULTS
  Most assays showed excellent peer performance attributes, except for HDL- and LDL cholesterol. Cases in which individual assays had biases exceeding the used limits were the Siemens Advia creatinine (-4.2%), Ortho Vitros phosphate (8.9%), Beckman Coulter AU triglycerides (5.4%), and Thermo Scientific Konelab uric acid (6.4%), which lead to considerable interassay discrepancies. Additionally, large laboratory effects were observed that caused interlaboratory differences of >30%.
  
  
  CONCLUSIONS
  The design of the EQA study was well suited for monitoring different quality attributes of assays performed in daily laboratory practice. There is a need for improvement, even for simple clinical chemistry analytes. In particular, the interchangeability of results remains jeopardized both by assay standardization issues and individual laboratory effects.
authors.affiliation: Laboratory for Analytical Chemistry, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium;
authors.forename: Hedwig C M
authors.initials: HC
authors.lastname: Stepman
authors.affiliation: Labquality, Helsinki, Finland;
authors.forename: Ulla
authors.initials: U
authors.lastname: Tiikkainen
authors.affiliation: STT-Consulting, Horebeke, Belgium;
authors.forename: Dietmar
authors.initials: D
authors.lastname: Stöckl
authors.affiliation: Centers for Disease Control and Prevention (CDC), Division of Laboratory Sciences, Atlanta, GA.
authors.forename: Hubert W
authors.initials: HW
authors.lastname: Vesper
authors.affiliation: Centers for Disease Control and Prevention (CDC), Division of Laboratory Sciences, Atlanta, GA.
authors.forename: Selvin H
authors.initials: SH
authors.lastname: Edwards
authors.affiliation: Labquality, Helsinki, Finland;
authors.forename: Harri
authors.initials: H
authors.lastname: Laitinen
authors.affiliation: Labquality, Helsinki, Finland;
authors.forename: Jonna
authors.initials: J
authors.lastname: Pelanti
authors.affiliation: Laboratory for Analytical Chemistry, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium; linda.thienpont@ugent.be.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Thienpont
mesh_terms: D001786:Blood Glucose / Q000032:analysis*; D002784:Cholesterol / Q000097:blood*; D019411:Clinical Laboratory Techniques / Q000592:standards*; D003404:Creatinine / Q000097:blood*; D006801:Humans; D010710:Phosphates / Q000097:blood*; D012680:Sensitivity and Specificity; D014280:Triglycerides / Q000097:blood*; D014527:Uric Acid / Q000097:blood*
chemical_list: D001786:Blood Glucose; D010710:Phosphates; D014280:Triglycerides; D014527:Uric Acid; D002784:Cholesterol; D003404:Creatinine