Naylor, DavidDicker, BridgetHowie, GrahamTodd, Verity2025-05-122025-05-122025-05-02Emerg Med Australas, ISSN: 1742-6731 (Print); 1742-6723 (Online), Wiley, 37(3), e70047-. doi: 10.1111/1742-6723.700471742-67311742-6723http://hdl.handle.net/10292/19181Early Warning Scores (EWS) have been developed to identify patients at risk of deterioration. Although the application of EWS has become increasingly established in the prehospital setting, their use remains contentious. The aim of this systematic review is to summarise the most recent evidence on the predictive accuracy of the EWS for short-term mortality in adults in the prehospital setting. A systematic search was conducted using the Medline, CINAHL, and Scopus databases. Studies that evaluated the diagnostic accuracy of the prehospital Modified Early Warning Score, National Early Warning Score or National Early Warning Score 2 in predicting mortality were included. Secondary outcomes were intensive care unit (ICU) admission and hospital admission. The review included 16 studies published between 2012 and 2023, with the number of patients totalling 311 932. The literature indicated that prehospital EWS demonstrated a moderate to good diagnostic performance in predicting short-term mortality with an area under receiver operating characteristic curve ranging from 0.68 (95% confidence interval [CI]: 0.64-0.73) to 0.90 (95% CI: 0.82-0.97). Overall, diagnostic performance was higher for predicting mortality in short time frames (up to 48 h). The need to use relatively high cut-off points to identify at-risk patients may limit its use for the unselected patient populations found in the prehospital setting. The potential for under-triage and over-triage limits their use further. EWS should not replace structured clinical evaluation and judgement but may be useful as complementary and objective tools to aid the identification of patients at risk.© 2025 The Author(s). Emergency Medicine Australasia published by John Wiley & Sons Australia, Ltd on behalf of Australasian College for Emergency Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.http://creativecommons.org/licenses/by/4.0/early warning scoreemergency servicemortalityout of hospitalparamedicprehospital32 Biomedical and Clinical Sciences3202 Clinical SciencesPatient Safety4.2 Evaluation of markers and technologiesGeneric health relevance3 Good Health and Well Being1103 Clinical Sciences1117 Public Health and Health ServicesEmergency & Critical Care Medicine3202 Clinical sciencesHumansEarly Warning ScoreEmergency Medical ServicesMortalityPredictive Value of TestsHumansMortalityPredictive Value of TestsEmergency Medical ServicesEarly Warning ScoreHumansEarly Warning ScoreEmergency Medical ServicesMortalityPredictive Value of TestsJournal ArticleOpenAccess10.1111/1742-6723.70047