Screening strategies to identify sepsis in the prehospital setting: a validation study

Abstract

Background: In the prehospital setting, differentiating patients who have sepsis from those who have infection but no organ dysfunction is important to initiate sepsis treatments appropriately. We aimed to identify which published screening strategies for paramedics to use in identifying patients with sepsis provide the most certainty for prehospital diagnosis.

Methods: We identified published strategies for screening by paramedics through a literature search. We then conducted a validation study in Alberta, Canada, from April 2015 to March 2016. For adult patients (≥ 18 yr) who were transferred by ambulance, we linked records to an administrative database and then restricted the search to patients with infection diagnosed in the emergency department. For each patient, the classification from each strategy was determined and compared with the diagnosis recorded in the emergency department. For all strategies that generated numeric scores, we constructed diagnostic prediction models to estimate the probability of sepsis being diagnosed in the emergency department.

Results: We identified 21 unique prehospital screening strategies, 14 of which had numeric scores. We linked a total of 131 745 eligible patients to hospital databases. No single strategy had both high sensitivity (overall range 0.02-0.85) and high specificity (overall range 0.38-0.99) for classifying sepsis. However, the Critical Illness Prediction (CIP) score, the National Early Warning Score (NEWS) and the Quick Sepsis-Related Organ Failure Assessment (qSOFA) score predicted a low to high probability of a sepsis diagnosis at different scores. The qSOFA identified patients with a 7% (lowest score) to 87% (highest score) probability of sepsis diagnosis.

Interpretation: The CIP, NEWS and qSOFA scores are tools with good predictive ability for sepsis diagnosis in the prehospital setting. The qSOFA score is simple to calculate and may be useful to paramedics in screening patients with possible sepsis.

Figure 1:

Study flow diagram. Note: EMS = emergency medical services. *These frequencies are not mutually exclusive. †For the 5632 patients with unmatched records, age and sex were as follows: 3667 patients were 18–65 years of age, and 1965 patients were older than 65 years; 3496 patients were women, and 2136 were men.

Figure 2:

Comparison of the predicted probability of a diagnosis of sepsis according to 14 numeric scores for patients with infection diagnosed in the emergency department. Note: The x axis was scaled from minimum to maximum for each score to allow for comparison of scores with a different number of points. Broken lines indicate scores with more than 5 possible points. The dot on each line represents the recommended threshold score for a diagnosis of sepsis (if available). BAS = Blood Pressure Andningsfrekvens (“respiratory rate” in Swedish) Saturation, Borrelli = Borrelli et al., CIP = Critical Illness Prediction score, HEWS = Hamilton Early Warning Score, MEWS = Modified Early Warning Score, NEWS = National Early Warning Score, PreSAT = Prehospital Sepsis Assessment Tool, PRESEP = Prehospital Early Sepsis Detection, PRESS = Prehospital Severe Sepsis, PSP = Prehospital Sepsis Project, qSOFA = Quick Sepsis-Related Organ Failure Assessment, Robson = Robson score (originally validated by Wallgren et al.53), SEPSIS = Screening to Enhance Prehospital Identification of Sepsis, SIRS = Systemic Inflammatory Response Syndrome.