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Published on: February 16, 2022
Differential absolute plasma IL-6 concentrations between two immunoassay platforms in intensive care unit patients
Pavan K Bhatraju1,2,3, Eric D Morrell1,2, Nicholas G O'Connor1
1Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of Washington, Seattle, 98104 WA, USA.
Abstract:
Objectives: Explore whether plasma IL-6 levels are similar across biomarker platforms and association with COVID-19 clinical outcomes. Methods: Plasma IL-6 concentrations were measured on 191 COVID-19 patients using the Roche Elecsys IL-6 assay and the Meso Scale Discovery assay. Results: Correlation of IL-6 levels between platforms was high (r = 0.87; 95% CI: 0.82-0.89); however, agreement was low (bias: 147.2 pg/ml; 95% limits of agreement: -489.5-783.9 pg/ml). The optimal IL-6 threshold to predict invasive mechanical ventilation and in-hospital mortality were 3- and 3.4-fold higher in Roche compared with Meso Scale Discovery, respectively. Conclusion: The absolute IL-6 threshold to predict outcomes was consistently higher using the Roche platform, and IL-6 thresholds to inform prognosis vary based on the biomarker platform.
