Plasma level of soluble urokinase-type plasminogen activator receptor as a predictor of disease severity and case fatality in patients with bacteraemia: a prospective cohort study

Abstract

Objectives: Urokinase-type plasminogen activator receptor (uPAR) is expressed on a variety of different immune cells and vascular endothelial cells during inflammation. Previous studies indicate that a high plasma concentration of the soluble form of the receptor (suPAR) predicts poor outcome in infectious diseases.

Design: A prospective cohort study.

Subjects and methods: Plasma suPAR levels were measured in 132 patients with bacteraemia caused by Staphylococcus aureus, Streptococcus pneumoniae, ß-haemolytic streptococcae or Escherichia coli using a commercial enzyme-linked immunosorbent assay (ELISA). Values were measured on days 1-4 after a positive blood culture, on days 13-18 and on recovery.

Results: The maximum suPAR values on days 1-4 were markedly higher in nonsurvivors compared to survivors (15.8 vs. 7.3 ng mL(-1) , P < 0.001) and the area under the receiver operating characteristic curve (AUC(ROC) ) in the prediction of case fatality was 0.84 (95% confidence interval (CI) 0.76-0.93, P < 0.001). At a cut-off level of 11.0 ng mL(-1) , the sensitivity and specificity of suPAR for fatal disease was 83% and 76%, respectively. A high level of suPAR (≥ 11 ng mL(-1) ) was associated with hypotension (mean arterial pressure < 70 mmHg) (odds ratio (OR) 6.5; 95% CI 2.9-14.6) and high sequential organ failure assessment score (≥ 4) (OR 9.3; 95% CI 4.0-21.9). A high suPAR level remained an independent risk factor for case fatality in a logistic regression model adjusted for potential confounders.

Conclusion: Plasma suPAR level is a sensitive and specific independent prognostic biomarker in patients with bacteraemia.