title: Systematic differences between BNP immunoassays: comparison of methods using standard protocols and quality control materials.
abstract: BACKGROUND
  Recent studies suggested that there are marked systematic differences among BNP immunoassays. In this study we compared the BNP data and clinical results obtained with different immunoassays, including a new method (ST-AIA-PACK, TOSOH Corporation).
  
  
  METHODS
  BNP was measured on plasma-EDTA samples of healthy subjects (HS, n=126) and patients with heart failure (HF, n=31 NYHA I, II; n=46 NYHA III, IV) using the ST-AIA-PACK and the Triage Biosite (Beckman Coulter) methods. Control samples distributed in the CardioOrmoCheck external quality assessment were also measured with TOSOH and the most used BNP immunoassays in Italy.
  
  
  RESULTS
  TOSOH method showed a good correlation (R=0.976; n=327) but a mean bias (-46.9%) compared to Triage Biosite. On the base of the results obtained in 10 samples of the CardioOrmoCheck study, TOSOH method showed a strict agreement with ADVIA Centaur, while it underestimated BNP in comparison with Triage (-52.5%) and ARCHITECT methods (-39.4%). The agreement of ST-AIA-PACK and Triage Biosite methods for classification of HF patients was tested using 100 ng/L of BNP; the positive agreement between methods was 65%, overall agreement was 73%.
  
  
  CONCLUSIONS
  Our results confirm that there are marked differences in measured values among commercial methods for BNP assay.
authors.affiliation: Scuola Superiore Sant'Anna, Pisa, Italy; Department of Laboratory Medicine, Fondazione Toscana G. Monasterio, Pisa, Italy. Electronic address: franzinimaria@gmail.com.
authors.forename: Maria
authors.initials: M
authors.lastname: Franzini
authors.forename: Silvia
authors.initials: S
authors.lastname: Masotti
authors.forename: Concetta
authors.initials: C
authors.lastname: Prontera
authors.forename: Andrea
authors.initials: A
authors.lastname: Ripoli
authors.forename: Claudio
authors.initials: C
authors.lastname: Passino
authors.forename: Stefania
authors.initials: S
authors.lastname: Giovannini
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Zucchelli
authors.forename: Aldo
authors.initials: A
authors.lastname: Clerico
mesh_terms: D016022:Case-Control Studies; D006333:Heart Failure / Q000097:blood* / Q000175:diagnosis; D006801:Humans; D007118:Immunoassay / Q000379:methods / Q000592:standards* / Q000706:statistics & numerical data*; D007558:Italy; D007753:Laboratories / Q000592:standards; D057230:Limit of Detection; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D015588:Observer Variation; D011786:Quality Control; D015203:Reproducibility of Results
chemical_list: D020097:Natriuretic Peptide, Brain
keywords: BNP; Heart failure; Immunoassay; Method comparison; Quality control