The diagnostic and prognostic significance of soluble urokinase plasminogen activator receptor in Crimean-Congo hemorrhagic fever

Abstract

Background Crimean-Congo hemorrhagic fever (CCHF) is a potentially fatal disease caused by a tick-borne virus from the Bunyaviridae family. It has recently been reported that soluble urokinase-type plasminogen activator receptor (suPAR), secreted from endothelial cells and the mononuclear phagocyte system, one of the main targets of the CCHF virus, is a potential biomarker for several bacterial and viral infection diseases. Objectives This study was intended to determine the diagnostic and prognostic significance of suPAR levels in CCHF. Study design This retrospective study was conducted between June 2006 and August 2009 using plasma from patients monitored with a diagnosis of CCHF and from healthy blood donors. Levels of plasma suPAR were determined using an enzyme-linked immunosorbent assay (ELISA) kit according to the manufacturer's instructions. Results One hundred CCHF patients were enrolled in the study. The control group was made up of 53 healthy blood donors. suPAR values of 6.2 ± 4.2 were determined in the CCHF patients and of 2.3 ± 0.6 in the control group ( p < 0.0001). A suPAR level optimum diagnostic cut-off point of 3.06 ng/mL was determined, with an area underneath the ROC (AUROC) curve of 0.94 (95% CI: 0.89–0.97), sensitivity of 87% (95% CI: 79–93%), specificity of 92% (95% CI: 82–98%), PPV of 95% and NPV of 79%. Five of the patients died. suPAR was 18.4 ± 9.1 in the patients that died and 5.6 ± 2.6 in the survivors ( p = 0.034). In terms of mortality, suPAR level had an optimum diagnostic cut-off point of 10.6 ng/mL, AUROC of 0.97 (95% CI: 0.94–0.99), sensitivity of 100% (95% CI: 48–100%), specificity of 96% (95% CI: 90–99%), PPV of 50% and NPV of 100%. Conclusions Plasma suPAR level, a new biomarker, is a test that can be used in the differential diagnosis and monitoring of CCHF in patients admitted to hospital with suspected infection. The test is at the same time important in being a possible predictor of mortality.