Early Identification of Sepsis by Emergency Medical Services: Diagnostic Accuracy of Scoring Systems in a Retrospective Cohort

<b>Background/Objectives:</b> Emergency Medical Services (EMSs) frequently provide the first medical contact for sepsis patients, but recognition is challenging. This study thus aimed to determine how often EMSs suspect sepsis and to evaluate the diagnostic accuracy of the quick Sequential Organ Failure Assessment (qSOFA), the Prehospital Early Sepsis Detection (PRESEP) score, and the Modified Early Warning Score (MEWS). <b>Methods:</b> A retrospective observational study of all EMS transports to one emergency department during a one-month period in 2023 was conducted. Prehospital vital signs, EMS working diagnoses, and final in-hospital diagnoses were abstracted. Scores were calculated post hoc. The primary outcome was the diagnostic accuracy of the EMSs' working diagnosis of "suspected sepsis." Secondary outcomes included the sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) of qSOFA, PRESEP, and MEWS. <b>Results:</b> Among 786 EMS encounters, 597 met the inclusion criteria. Twelve patients (2.0%) were ultimately diagnosed with sepsis. EMSs explicitly suspected sepsis in three of them (25.0%; sensitivity 16.7%, specificity 99.8%). Retrospective application of scores yielded markedly higher sensitivity: qSOFA 83.3%, PRESEP 91.7%, and MEWS 83.3%. Specificities were 74.2% for qSOFA, 41.2% for PRESEP, and 77.6% for MEWS. The AUCs were 0.838 for qSOFA, 0.695 for PRESEP, and 0.863 for MEWS, with MEWS significantly outperforming PRESEP (<i>p</i> = 0.0215). <b>Conclusions:</b> EMS personnel rarely labeled patients with sepsis, recognizing 3 of 12 cases (25%). Retrospective use of scoring systems based on routine vital signs substantially improved diagnostic accuracy, with MEWS performing best overall. Structured screening tools should be prospectively validated and potentially implemented in EMS.