DOI: 10.2217/bmm-2023-0073 ISSN:

Differential absolute plasma IL-6 concentrations between two immunoassay platforms in intensive care unit patients with COVID-19

Pavan K Bhatraju, Eric D Morrell, Nicholas G O'Connor, Audrey Choi, Michael Fitzpatrick, Craig H Smith, Mark M Wurfel, Wayne Conrad Liles
  • Biochemistry (medical)
  • Clinical Biochemistry
  • Drug Discovery

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– to 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.

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