ABSTRACT
Introduction: Calprotectin plays an important role in the inflammatory response and its levels were significantly increased in patients with various inflammatory and autoimmune conditions. Calprotectin is located in the cytosol of neutrophils and is released after their activation. The aim of the study was to evaluate the prognostic role of serum circulating calprotectin in COVID-19 patients. Patients and Methods: We retrospectively analyzed data about 195 COVID-19 adult patients, 10 of which resulting in a fatal outcome. Circulating calprotectin and C-reactive protein (CRP) levels were measured with the ACHITECT i2000R System (Abbott Laboratories, Wiesbaden, Germany). Complete blood count was obtained by a standard method on ADVIA 2120 Hematology System (Siemens Healthcare). Result(s): Calprotectin levels and neutrophil counts were higher in patients with a fatal outcome respect to surviving patients: 4.26 (2.01-9.84) vs 1.28 (0.54-3.60) with p=0.006 and 20.26 (8.29-30.26) vs 6.57 (4.74-9.38) with p=0.002.Calprotectin levels correlated with levels CRP (Spearman coefficient 0.354, p<0.001) and neutrophil count (Spearman coefficient 0.350, p<0.001). Both high calprotectin levels and high neutrophil counts were associated with death at multivariate analysis.Multivariate analysis revealed the association with death of both calprotectin levels and neutrophil count, with an odds ratio (OR) higher for calprotectin levels 1.843 (1.292-2.630)p=0.001. ROC curve analysis of calprotectin levels revealed a good discriminating power toward survival with an AUC=0.759 (p=0.0004). The best cut-off value for calprotectin was 1.66 mg/L with a sensitivity of 90% and specificity of 58.9%. To test the prognostic value of this cut-off of calprotectin levels toward the exitus, a Kaplan-Meier analysis was performed. Log-rank test revealed a statistical difference in terms of survival between the two groups (p< 0.0005). Conclusion(s): Calprotectin levels higher than 1.66 mg/L are a predictor of mortality and can be used as a prognostic marker in patients with COVID-19. Calprotectin levels were more efficient in the outcome evaluation than other inflammatory markers, probably because it represents a marker of neutrophil activation.