suPAR evaluation in patients with SARS-CoV-2 infection: our experience

ABSTRACT

Introduction Elevated soluble urokinase Plasminogen Activator Receptor (suPAR) is a biomarker associated with adverse outcomes. We aimed to investigate the associations among plasma suPAR levels (testing the cut-offs <=4 and >=6 ng/mL that supports patient discharge/hospitalisation, respectively) with other biomarkers such as PCR, PCT, IL-6 and with sex, age, discharge/death and WHO disease severity in patients tested positive for SARS-CoV-2. Methods We performed an observational cohort study of 99 patients (37 females, 62 males) presenting with COVID-19 symptoms at Department of Infectous and Critical Care of our Hospital in April 2020. Plasma suPAR was measured using suPARnostic kit (Virogates, Denmark), an immunoturbidimetric method on Abbott Alinity i platform. Patients were followed for development of mechanical ventilation, mortality or discharged. Statistical analysis was performed using Principal Component Analysis (PCA) that can be applied to datasets to obtain a simplified model for stratifying patients by reducing the number of variables. PCA weights the variables according to their relative importance. This method, in our case, can aid in determining key variables in management of patients affected by SARS-CoV-2. Results The mean age was 58 years;women had a higher concentration average of suPAR (8.9 vs 8.3 ng/mL) but the subdivision by sex did not determine any clustering. All variables showed a positive correlation with disease severity, better with IL-6 and suPAR (IL-6=25.3%, suPAR=24%, age=16.4%, PCT=15.4%, PCR=17.2%), allowing a subdivision of 3 groups (severe/ critic IL-6=227.65 pg/mL, suPAR=9.26 ng/mL;moderate IL-6=48.1 pg/mL, suPAR=7.35 ng/mL, paucisymptomatic IL-6=3.7 pg/mL, suPAR=2.78 ng/mL). Combining the variables and discharge/death outcome showed positive correlation although this did not result any clear clustering (n.78 discharged IL-6=214 pg/mL, suPAR=8.23 ng/mL;n.14 dead IL-6=286 pg/mL, suPAR=11.31 ng/mL). Discussion Our data show that suPAR levels increase as the disease worsens. Statistical analyses demonstrated that suPAR levels are positively correlated with age and IL-6 levels. Therefore, further evaluation of suPAR plasma levels in different symptoms of COVID-19 patients could still provide important indications for early admission and treatment.