The Value of Soluble Urokinase Plasminogen Activator Receptor (suPAR) as Predictive Tool in Hospitalised Patients With Community-Acquired Pneumonia (CAP)

Abstract

Background: Soluble urokinase plasminogen activator receptor (suPAR) is a biomarker elevated in severely ill patients, but its prognostic value in community-acquired pneumonia (CAP) remains unclear. This study aimed to evaluate suPAR's prognostic role for CAP severity compared to other biomarkers and severity scores.

Methods: A total of 204 hospitalised CAP patients were enrolled. C-reactive protein (CRP), procalcitonin (PCT), suPAR, CURB-65 and Pneumonia Severity Index (PSI) scores were measured at admission, and patients were followed for 365 days. The primary outcome was the relationship between suPAR levels and CAP severity based on IDSA/ATS guidelines. Secondary outcomes included time to clinical stability (TTCS), length of stay (LOS) and mortality.

Results: Among 204 patients, 174 (85%) had non-severe and 30 (15%) had severe CAP. SuPAR levels were not associated with severe CAP (OR 1.03, 95% CI 0.88-1.21; AUC 0.53). Unlike the PSI and CURB-65 scores, suPAR did not correlate with TTCS (HR PSI 0.80, HR CURB-65 0.86), though all three markers were correlated to LOS (AUC suPAR 0.61). Only suPAR was significantly associated with 30-day mortality (HR 1.51, AUC 0.68).

Conclusions: The prognostic value of suPAR for CAP severity is low, and it does not provide additional prognostic benefit over the CURB-65 or PSI scores in predicting CAP severity. While it has moderate predictive ability for 30-day mortality, its utility for predicting LOS or TTCS is low.

Trial registration: ClinicalTrials.gov identifier: NCT01964495.

Keywords: biomarkers; pneumonia; prognosis; severity.