The most frequent keywords reflecting clinical presentation in the entire sample of septic patients arriving to the ED were: “abnormal, or suspected abnormal temperature”, “pain”, “abnormal breathing”, “risk factors for sepsis”, “abnormal circulation”, “temporal deterioration”, “gastrointestinal symptoms”, “acute altered mental status”, “abnormal urination”, “loss of energy” and “decreased mobility”. Keywords more common among septic patients arriving by EMS were: “abnormal breathing”, “abnormal circulation”, “acute altered mental status” and “decreased mobility”, while “pain” and “risk factors for sepsis” were more frequent among septic patients arriving to the ED by means other than EMS.
Keywords with a similar prevalence among patients arriving by EMS and non-EMS
The most common combined keyword among both patients arriving by EMS and by non-EMS was “abnormal, or suspected abnormal temperature”. Both fever and hypothermia have previously been described as symptoms related to the septic patient (3, 13). However, despite “abnormal, or suspected abnormal temperature” being the most prevalent keyword in the current study, approximately one third of the included patients did not present with fever. This finding is consistent with previous studies (3, 14).
“Temporal deterioration” represents an acute change in the patient’s habitual state, but it does not describe the details of this change. The prevalence of temporal deterioration was high both among EMS and non-EMS patients. These findings are consistent with those demonstrated by Bohm et al in emergency calls involving septic patients (15).
Vomiting and diarrhea were common among both patients arriving by EMS and by non-EMS. The high frequency of “gastrointestinal symptoms” in the current study is supported by previous studies (3, 13).
The keywords “abnormal skin”, “abnormal urination” and “loss of energy” were also present among patients arriving by both EMS and by non-EMS to a similar extent.
Keywords more frequent among patients arriving by EMS
“Abnormal circulation”, “abnormal breathing”, “acute altered mental status” and “decreased mobility” were all significantly more common among patients arriving by EMS. The first three are directly connected to the former criteria for severe sepsis (11) and the findings most likely reflect that EMS patients are more severely ill than non-EMS patients, which is also supported by previous studies (8).
Keywords more frequent among patients not arriving by EMS
“Pain” is an unspecific symptom and the single most common chief complaint among ED patients in general (16). That pain was more common among non-EMS patients could potentially be a consequence of the increased prevalence of acute altered mental status among patients arriving by EMS, in turn impairing the patient’s capability to express pain. Furthermore, keywords reflecting abnormal vital signs were more common among patients arriving by EMS patients and abnormal vital signs may render more attention among emergency care providers as compared to symptoms e.g. pain.
The combined keyword “risk factors for sepsis” includes several primary keywords such as ongoing or recent infection/ invasive procedures/ immunosuppressive treatment. Patients with such underlying conditions are often informed to seek medical attention if they deteriorate and may therefore seek medical attention at an earlier stage and hence need an ambulance to a lesser extent. In addition, patients with “risk factors for sepsis” have previously been shown to be younger (3) which may affect the capacity to use means of transportation other than the ambulance, but these speculations remain to be investigated.
Reflections on observed differences between patients arriving by EMS vs by non-EMS and clinical implementation of the results
Several factors are thought to contribute to the observed differences in keyword prevalence based on mode of arrival. We do not believe that the arrival mode per se exhibits causality on the presentation but rather that the observed differences reflect that patients arriving by EMS are older and have a higher prevalence of severe sepsis as compared with patients arriving by other means. This is supported by the stratification analyses showing that “abnormal circulation”, “acute altered mental status”and “decreased mobility” did not remain significantly more frequent among EMS patients and “risk factors for sepsis” did not remain significantly more frequent among non-EMS patients when stratified for sepsis severity, indicating that differences in sepsis severity accounts for the observed differences for these keywords between EMS vs non-EMS patients. The current results are of interest to demonstrate the principle of adapting sepsis screening tools to the population where they are planned to be implemented. How this should be done in detail requires further studies e.g. with respect to the specificity of the keywords.
Nevertheless, despite these observed differences, we would like to emphasize that most keywords demonstrated a similar distribution regardless of mode of arrival and the most prevalent keywords related to sepsis presentation in the current study confirm prior results from the prehospital (3, 15) and ED settings (13).
There are several limitations to the current study.
The definition of sepsis based on ICD-code can be questioned, as it is well known that identification of septic patients based on ICD codes leads to an underestimation of the true number of septic patients (17) and hence, there is a risk that the study sample may not be representative of all ED patients with sepsis. Inclusion based on ICD-code sepsis may involve a selection of the most severely ill septic patients. However, the method has been used in large epidemiological studies of sepsis (18) and is the only realistic method for larger registry studies.
Furthermore, the current study was a retrospective study with the inherent limitations of missing data. The prevalence of keywords was based on documented observations in ED records. Documentation may depend on various factors such as inter-individual variation among ED personnel and ED workload. Many of the keywords represent symptoms, and the identification of symptoms require a thorough history taking by the ED doctor in addition to a communicable patient.
Multiple comparisons were performed, with the inherent risk of inferring type I errors. Therefore, the level of significance was adjusted by applying a Bonferroni correction. However, the Bonferroni correction is excessively strict with the inherent risk of inferring type II errors . Hence, although erring on the side of caution, this may have resulted in true differences being regarded as non-significant.
Furthermore, when comparing the prevalence of especially primary keywords, the number of patients in the compared groups were few and hence the results must be interpreted with caution and need to be confirmed in larger samples.
Finally, the current study is a single center study which may limit the generalizability of the results. However, patients were included over a period of one year which enables the seasonal variation of sepsis to be accounted for. In addition, the study setting was the largest ED in Scandinavia at the time (9).