Elsevier

Resuscitation

Volume 89, April 2015, Pages 31-35
Resuscitation

Rapid Response Systems
Validation of the National Early Warning Score in the prehospital setting

https://doi.org/10.1016/j.resuscitation.2014.12.029Get rights and content

Abstract

Background

Early intervention and response to deranged physiological parameters in the critically ill patient improves outcomes. A National Early Warning Score (NEWS) based on physiological observations has been developed for use throughout the National Health Service (NHS) in the UK. Although a good predictor of mortality and deterioration in inpatients, its performance in the prehospital setting is largely untested. This study aimed to assess the validity of the NEWS in unselected prehospital patients.

Methods

All clinical observations taken by emergency ambulance crews transporting patients to a single hospital were collated along with information relating to hospital outcome over a two month period. The performance of the NEWS in identifying the endpoints of 48 h and 30 day mortality, intensive care unit (ICU) admission, and a combined endpoint of 48 h mortality or ICU admission was analysed.

Results

1684 patients were analysed. All three of the primary endpoints and the combined endpoint were associated with higher NEWS scores (p < 0.01 for each). The medium-risk NEWS group was associated with a statistically significant increase in ICU admission (RR = 2.466, 95% CI 1.0–6.09), but not in-hospital mortality relative to the low risk group. The high risk NEWS group had significant increases in 48 h mortality (RR 35.32 [10.08–123.7]), 30 day mortality (RR 6.7 [3.79–11.88]), and ICU admission (5.43 [2.29–12.89]). Similar results were noted when trauma and non-trauma patients were analysed separately.

Conclusions

Elevated NEWS among unselected prehospital patients is associated with a higher incidence of adverse outcomes. Calculation of prehospital NEWS may facilitate earlier recognition of deteriorating patients, early involvement of senior Emergency Department staff and appropriate critical care.

Introduction

Early intervention and response to deranged physiological parameters improves survival outcomes in both medical and surgical patients.1, 2, 3 To this end a number of early warning systems have been developed in recent years4 and have been shown to be good predictors of mortality and deterioration.5 Recent work by the Royal College of Physicians has led to the development of a National Early Warning Score (NEWS)6 which is currently implemented by the National Health Service (NHS) in acute hospitals across the UK and has been successful in identifying patients at risk of deterioration or death.7 More recently there has been adoption of early warning scores in some emergency departments8, 9, 10 although this has not been without controversy.11 The use of NEWS in the prehospital setting also remains controversial, partly due to lack of evidence.12, 13 As the development of this score involved analysis of clinical observations in hospital inpatients, in whom a course of treatment had already been started, uncertainty exists as to the applicability of the NEWS to other settings, particularly the emergency department and prehospital setting, where scores would be derived prior to the institution of any treatment. In this situation the score may contribute to a decision to transfer a patient to hospital14 or may be used as a triage aid, both of which roles differ slightly from the track and trigger (of a clinical review) role for which NEWS was originally intended.

The NEWS was based on the earlier ViEWS15 (VitalPAC Early Warning Score) developed in Portsmouth and stratifies patients into risk categories based on observed heart rate, respiratory rate, systolic blood pressure, arterial oxygen saturation, temperature, and conscious level; plus an additional weighting if the patient is being given oxygen therapy. Patients are then risk stratified based on the resulting aggregate score into low, medium, and high risk groups. Patients with a low aggregate score but who score in the highest category for any single observation are classified as at least medium risk (see Supp. Figs. 1 and 2).

This study, based in a large district general hospital in Paisley, on the western edge of the Greater Glasgow metropolitan area, Scotland, aimed to evaluate the performance of the NEWS in identifying patients at risk of death or deterioration in the prehospital setting.

Section snippets

Methods

Data protection approval to analyse and cross-reference patient-identifiable information was obtained from the Caldicott Guardians of both organisations involved (NHS Greater Glasgow and Clyde and Scottish Ambulance Service) prior to commencement of the study. Details of all emergency ambulance crews dispatched with an intention to transfer to the Royal Alexandra Hospital (RAH) were obtained from the Scottish Ambulance Service data warehouse, along with details of demographics, initial patient

Results

11,052 sets of clinical observations were obtained from 6028 unique patients. After exclusions, 1684 complete patient encounters were identified for study (see Supp. Fig. 3). All patients were transported by emergency ambulances staffed either by two paramedics or one paramedic and one emergency ambulance technician. Table 1 shows a description of the patient population studied.

Discussion

Triage is a crucial part of any unplanned care system, and has been developed significantly since its inception during the Napoleonic Wars. Algorithms such as the Manchester Triage System16 provide objective criteria for the allocation of patients to care areas, and can be sensitive enough to detect the signs of critical illness at the point of entry to the emergency department although they may still miss patients with the possibility of deterioration while still in the Emergency Department.17

Limitations

This study does have some limitations. We have not adjusted for age or sex differences between the low, medium and high risk NEWS groups, and this may account for some of the difference in mortality. However, the absence of age or gender adjustments is a feature of the NEWS that our study aimed to validate. As one of the end-points was survival to discharge and only in-hospital death was considered, the mortality rate, particularly the 30day mortality rate, may be underestimated. Similarly, due

Conclusion

Elevated NEWS among unselected prehospital patients is associated with increased levels of adverse outcomes. Calculation of an early warning score prior to transfer to hospital is straightforward and may be a useful triage tool with potential to facilitate earlier recognition of at-risk or deteriorating patients, possibly allowing earlier involvement of appropriate ED and critical care staff.

Conflict of interest statement

No conflicts of interest to declare.

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    A Spanish translated version of the summary of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2014.12.029.

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