title: Multicenter evaluation of analytical characteristics of the Elecsys®Periostin immunoassay.
abstract: OBJECTIVE
  The multifunctional cytokine IL-13 is thought to play a central role in Type 2 inflammation in asthma. Serum periostin has been explored as a candidate biomarker for evaluating IL-13 activity in the airway. We describe the technical performance characteristics of a novel, fully automated immunoassay for the determination of periostin in serum.
  
  
  METHODS
  Limit of blank [LoB], limit of detection [LoD] and limit of quantitation [LoQ], linearity, precision and reproducibility across sites and lots were evaluated according to Clinical and Laboratory Standards Institute guidelines. Interferences and sample stability were also investigated.
  
  
  RESULTS
  The pre-specified values for LoB (2ng/mL), LoD (4ng/mL) and LoQ (10ng/mL) were met. The assay was linear throughout the measuring range (10-160ng/mL) with recoveries within ±10% of target at concentrations >30ng/mL and within ±3ng/mL at concentrations ≤30ng/mL. Recovered periostin concentrations were also within ±10% of target in presence of 43 potentially interfering substances and drugs. Samples were stable across various storage conditions and durations (24h at room temperature, 7days at 4°C, 12weeks at -20°C, and 3 freeze/thaw cycles). Repeatability experiments resulted in CVs across samples and controls ranging from 0.9-1.5%. Intermediate precision was 1.2-1.7% and reproducibility including 3 testing sites and 3 reagent lots was 1.7-3.1%. The final assay correlates to the assay version used in previous clinical trials (Pearson's r=0.998, bias at 50ng/mL=1.2%).
  
  
  CONCLUSIONS
  The performance evaluation of the Elecsys®Periostin immunoassay including a multicenter precision analysis demonstrated that the assay is suitable for measuring serum periostin at clinically important concentrations around 50ng/mL.
authors.affiliation: Roche Professional Diagnostics, Penzberg, Germany. Electronic address: Stefan.palme@roche.com.
authors.forename: Stefan
authors.initials: S
authors.lastname: Palme
authors.affiliation: School of Medicine, University of Maryland, Baltimore, MD, USA. Electronic address: rchristenson@umm.edu.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Christenson
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Louisville, Louisville, KY, USA. Electronic address: saeed.jortani@louisville.edu.
authors.forename: Saeed A
authors.initials: SA
authors.lastname: Jortani
authors.affiliation: Division of Endocrinology, Metabolism and Lipid Research, School of Medicine, Washington University in St. Louis, St. Louis, MO, USA. Electronic address: rostlund@wustl.edu.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Ostlund
authors.affiliation: Roche Professional Diagnostics, Penzberg, Germany. Electronic address: ruediger.kolm@roche.com.
authors.forename: Ruediger
authors.initials: R
authors.lastname: Kolm
authors.affiliation: Roche Professional Diagnostics, Penzberg, Germany. Electronic address: guido.kopal@roche.com.
authors.forename: Guido
authors.initials: G
authors.lastname: Kopal
authors.affiliation: Roche Professional Diagnostics, Penzberg, Germany; Institute of Medical Informatics, Biometry, and Epidemiology, Faculty of Medicine, University of Munich, Munich, Germany. Electronic address: ruediger.laubender@roche.com.
authors.forename: Ruediger P
authors.initials: RP
authors.lastname: Laubender
mesh_terms: D015415:Biomarkers / Q000032:analysis; D015815:Cell Adhesion Molecules / Q000032:analysis; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D015203:Reproducibility of Results
chemical_list: D015415:Biomarkers; D015815:Cell Adhesion Molecules; C512835:POSTN protein, human
keywords: Biomarker; Elecysis(®); Immunoassay; Periostin; Precision; Type 2 asthma