The Soluble Urokinase Plasminogen Activator Receptor as a Severity Biomarker in Children With Acute COVID-19 or Multisystem Inflammatory Syndrome

Background: Elevated soluble urokinase plasminogen activator receptor (suPAR) has been associated with a poor prognosis in serious infections. The aim of this study was to evaluate the clinical value of suPAR in children with acute coronavirus disease 2019 (COVID-19) or multisystem inflammatory syndrome (MIS-C). Methods: Serum suPAR was measured using the suPARnostic AUTO Flex enzyme-linked immunosorbent assay in hospitalized children with COVID-19, MIS-C, bacterial pneumonia, and healthy controls. Results: A total of 211 children with a mean (+/- SD) age of 6.9 +/- 4.96 years were tested; with COVID-19: 59 (28%), MIS-C: 36 (17%), pneumonia: 78 (37%) and healthy controls: 38 (18%). In the acute phase, the levels of suPAR (mean +/- SD) were: MIS-C: 8.11 +/- 2.80 ng/mL, COVID-19: 4.91 +/- 1.90 ng/mL, pneumonia: 4.25 +/- 1.44 ng/mL and controls: 2.09 +/- 0.47 ng/mL (P < 0.001). Children with acute COVID-19 and a severe or moderate clinical presentation had higher values than those with mild symptoms: 5.79 +/- 1.58 versus 5.40 +/- 1.94 versus 3.19 +/- 0.73 ng/mL, respectively (P < 0.001). In the MIS-C group, children hospitalized in the intensive care unit and in need of mechanical ventilation had higher suPAR than those who were not admitted to an intensive care unit: 9.32 +/- 3.06 versus 7.13 +/- 2.19 ng/mL, respectively (P = 0.023). In children with COVID-19 or MIS-C, a correlation was detected between suPAR values and length of hospitalization (rs = 0.418, P < 0.001). Conclusions: The findings suggest that suPAR may be a valuable biomarker of disease severity in children with COVID-19 or MIS-C. This could facilitate the identification of children in need of intensive anti-inflammatory treatment, as it has been shown in adults with severe COVID-19.