Background
SuPAR is a prognostic biomarker in severely ill patients. Levels >6 ng/ml are an indicator of high inflammation. We aimed to determine the prognostic value of suPAR for severity and patient outcome in CAP.

Methods
A total of 204 patients hospitalized with CAP were enrolled. C-reactive protein (CRP), procalcitonin (PCT), suPAR, CURB-65 score and PSI score were determined at admission. Time-dependent receiver-operator characteristic (ROC) curves for time to clinical stability (TTCS, at day 7), length of stay (LOS, at day 14) and in-hospital mortality (at day 30) were calculated.

Results
The median age was 69 years (IQR 60-80). SuPAR and PCT, but not CRP, were significantly higher in patients with a higher CURB-65 score. SuPAR, but not PCT and CRP, was significantly higher in patients with a higher PSI class. The Area Under the Curve (AUC) of supAR for TTCS was 0.55 (95% CI 0.43-0.67), the AUC for LOS was 0.68 (0.51-0.84) and the AUC for mortality was 0.66 (0.34-0.97). The difference in AUC of suPAR vs. other predictors was not significant for any of the curves, except for suPAR vs. PCT in the ROC curve of mortality (p=0.04).

Conclusions
SuPAR at admission showed higher correlation with CAP severity scores than PCT and CRP.
Predictive ability of suPAR for TTCS, LOS and mortality was moderate and similar to the predictive ability of PCT, CRP, the PSI score and the CURB65-score.