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. Design and 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 (2 ng/mL), LoD (4 ng/mL) and LoQ (10 ng/mL) were met. The assay was linear throughout the measuring range (10–160 ng/mL) with recoveries within ± 10% of target at concentrations > 30 ng/mL and within ± 3 ng/mL at concentrations ≤ 30 ng/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 (24 h at room temperature, 7 days at 4 °C, 12 weeks 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 50 ng/mL = 1.2%). Conclusion 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 50 ng/mL.
- Type 2 asthma