C-reactive protein and clinical outcome in COVID-19 patients: the importance of harmonized measurements

C-reactive protein (CRP) is a cytokine-mediated
acute phase reactant with a recognized role in inflammatory
conditions and infectious disease. In coronavirus disease
2019 (COVID-19), elevated CRP concentrations in serum were
frequently detected and significantly associated with poor
outcome in terms of disease severity, need for intensive care,
and in-hospital death. For these reasons, the marker was
proposed as a powerful test for prognostic classification of
COVID-19 patients. In most of available publications, there
was however confounding information about how interpretative criteria for CRP in COVID-19 should be derived,
including quality of employed assays and optimal cut-off
definition. Assuring result harmonization and controlling
measurement uncertainty in terms of performance specifications are fundamental to allow worldwide application of
clinical information according to specific CRP thresholds and
to avoid risk of patient misclassification.