title: Multicenter analytical evaluation of the automated electrochemiluminescence immunoassay for cyclosporine.
abstract: BACKGROUND
  Cyclosporine A (CsA) is used as a posttransplantation immunosuppressant drug, and careful monitoring of CsA concentration in whole blood is essential. A new automated electrochemiluminescence immunoassay (ECLIA) for CsA measurement has been assessed in a multicenter evaluation.
  
  
  METHODS
  Residual EDTA whole blood samples from patients undergoing CsA therapy after organ transplant were used in assay evaluation at 5 clinical laboratories in Europe. Experiments included imprecision according to CLSI EP5-A2 (within-run and intermediate), lower limit of quantification, linearity according to CLSI EP6-A, and recovery of commercial external quality control samples. In addition, comparisons to liquid chromatography-tandem mass spectrometry methods in routine use at each investigational site and to commercial chemiluminescent microparticle immunoassay and antibody-conjugated magnetic immunoassay methods were performed.
  
  
  RESULTS
  Imprecision testing gave coefficients of variation of less than 9% in the 30-2000 mcg/L range for both within-run and intermediate imprecision. Lower limit of quantification of 6.8 mcg/L at one investigational site and 1.8 mcg/L at a second site at 20% coefficient of variation were observed. Linearity was measured over the concentration range 0-2000 mcg/L, yielding a deviation of less than ±12%. External quality control sample recovery by ECLIA was 93%-114% of LC-MS/MS sample recovery. Deming regression analysis of ECLIA method comparison to combined LC-MS/MS results yielded a slope of 1.04 [95% confidence interval (CI), 1.03-1.06] and intercept of 2.8 mcg/L (95% CI, 1.5-4.1 mcg/L). Comparison to chemiluminescent microparticle immunoassay yielded a slope of 0.87 (95% CI, 0.85-0.89) and intercept of 1.4 mcg/L (95% CI, -0.89 to 3.7 mcg/L); comparison to antibody-conjugated magnetic immunoassay yielded a slope of 0.96 (95% CI, 0.93-0.98) and intercept of -4.2 mcg/L (95% CI, -7.1 to -1.2 mcg/L).
  
  
  CONCLUSIONS
  The data from this multicenter evaluation indicate that the new ECLIA-based cyclosporine assay is fit for its purpose, the therapeutic monitoring of CsA.
authors.affiliation: *Hospital of the University of Munich, Institute of Laboratory Medicine; †Central Institute of Clinical Chemistry and Laboratory Medicine, Klinikum-Stuttgart, Germany; ‡Laboratori Clínic Department, Hospital Universitari de Bellvitge, Barcelona, Spain; §Cliniques Universitaires St. Luc, Louvain Toxicology and Applied Pharmacology, Université Catholique de Louvain, Brussels, Belgium; ¶Institue for Laboratory Medicine, Marienhospital, Stuttgart; ‖Roche Diagnostics GmbH, Mannheim, Germany; and **Department of Laboratory Medicine, Ghent University and Ghent University Hospital, Belgium.
authors.forename: Michael
authors.initials: M
authors.lastname: Vogeser
authors.forename: Maria
authors.initials: M
authors.lastname: Shipkova
authors.forename: Raül
authors.initials: R
authors.lastname: Rigo-Bonnin
authors.forename: Pierre
authors.initials: P
authors.lastname: Wallemacq
authors.forename: Matthias
authors.initials: M
authors.lastname: Orth
authors.forename: Monika
authors.initials: M
authors.lastname: Widmann
authors.forename: Alain G
authors.initials: AG
authors.lastname: Verstraete
mesh_terms: D001331:Automation; D016572:Cyclosporine / Q000097:blood*; D016903:Drug Monitoring / Q000379:methods; D055664:Electrochemical Techniques / Q000379:methods*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007166:Immunosuppressive Agents / Q000097:blood*
chemical_list: D007166:Immunosuppressive Agents; D016572:Cyclosporine