Abstract / Summary
Soluble urokinase plasminogen activator receptor (suPAR) reflects systemic immune activation and biological vulnerability and has been proposed as a cross-diagnostic prognostic biomarker in emergency care. We systematically reviewed full-text English-language reports published from 1 January 2015 through 20 July 2026 in PubMed/MEDLINE and Scopus. Eligible studies measured plasma or serum suPAR at emergency-department presentation, first acute medical contact, or a directly linked prehospital encounter and reported mortality, deterioration, disposition, length of stay, readmission, incremental prediction, or clinical-impact outcomes. The searches identified 130 records (PubMed/MEDLINE, 66; Scopus, 64). After removal of 39 duplicates, 91 unique records were screened, 54 reports were assessed as full texts, and 43 reports representing 34 coded cohort families were included. Because assay platforms, exposure scales and cut-offs, populations, outcome horizons, effect measures, adjustment sets, and overlapping cohorts were not sufficiently commensurate for a clinically interpretable pooled estimate, the evidence was synthesized narratively using a structured SWiM approach. Higher suPAR was generally associated with short- and longer-term mortality across heterogeneous populations, although residual confounding, assay differences, data-derived cut-offs, and limited external validation reduced certainty. Reported cut-offs were study-specific: <4 ng/mL was evaluated for low-risk enrichment in acute medical and short-stay cohorts, 6 ng/mL in suspected-infection and other acute-care cohorts, 8 ng/mL in one prehospital mortality study, and 12 ng/mL with qSOFA = 1 in the SUPERIOR pathway. Because assay platforms, populations, outcomes, and threshold derivation/validation strategies differed, no universal decision threshold was supported. suPAR improved discrimination or reclassification beyond NEWS, qSOFA, or other clinical models in some studies, but prediction-model risk of bias was frequently high. A large cluster-randomized trial found no mortality benefit from routine biomarker availability, and evidence for discharge, length of stay, readmission, or protocolized treatment remained context-dependent. Certainty was very low for short-term prognostic association, incremental prediction, and most clinical-impact outcomes, whereas the available evidence was insufficient to support a universal suPAR decision threshold; certainty was moderate for the absence of a mortality benefit from routine biomarker availability. suPAR may complement structured acute-care assessment but should not be used as a standalone admission, discharge, intensive care, or treatment rule.