Analytical and clinical evaluation of a novel assay for measurement of interleukin 6 in human whole blood samples.

ABSTRACT

BACKGROUND: Interleukin 6 assays are useful in early detection of infections and risk stratification of critically ill patients, so an assay with a short turnaround-time and near-patient use is preferred. This study evaluated the performance of a new interleukin 6 assay, Pylon IL-6 assay, and explored its potential use in near-patient settings. METHODS: We carried out imprecision, linearity and comparison studies using serum and plasma samples according to CLSI EP guidelines. The stability of whole blood samples during storage was assessed. Furthermore, whole blood samples from pediatric patients with suspected infection were measured to evaluate the assay's diagnostic performance. RESULTS: The within-run CVs and total CVs of Pylon IL-6 assay were determined as 1.8% and 3.0% at 159.3 pg/ml and 3.5% and 4.7% at 8009.9 pg/ml, respectively. The method showed linearity between 1.5 and 42,854 pg/ml. The results of serum samples measured by Pylon assays correlated to those measured by Roche assays, as well as to those of matched whole blood samples measured by Pylon assays. IL-6 in whole blood was found stable for ~8 h at room temperature. Pylon IL-6 results of whole blood samples from 179 pediatric patients with suspected infection showed an AUC of 0.842 in diagnosis of bacterial infection. The turnaround time of Pylon IL-6 assay was only 1 h when using whole blood samples. CONCLUSION: The new assay demonstrated performance comparable to those performed on clinical laboratory instruments and can be used in near-patient settings with whole blood to reduce turnaround times.