Review articleThe impact of the use of the Early Warning Score (EWS) on patient outcomes: A systematic review☆
Introduction
Acute deterioration in patients is often preceded by subtle changes in physiological parameters such as pulse, blood pressure, respiratory rate and level of consciousness.1, 2, 3, 4 Both prospective and retrospective chart reviews as well as a recent report published by the NCEPOD show that evidence of clinical deterioration is often present for hours prior to the occurrence of serious adverse events (SAEs) such as cardiac arrest, death and intensive care unit admission, leading to the conclusion that many of these SAEs might be preventable.3, 5, 6, 7, 8 Factors involved in ‘preventable’ SAEs frequently include poor clinical monitoring, inadequate interpretation of changes in physiological parameters and failure to undertake appropriate action.9, 10, 11, 12 Further, the inability to accurately recognize and initiate treatment of the critically unwell patient not only leads to higher levels of morbidity, but excessive utilization of costly resources, such as increased ICU usage and longer inpatient stay, a pressing issue in a climate of intense financial constraint.
Hospitals need tools to help them recognize patients at risk of deterioration in order to give the right care at the right moment before any SAEs arise The concept of the Early Warning Score (EWS), was developed in 1997 by Morgan et al.13 It consists of a simple to use algorithm based on physiological parameters, such as heart rate, systolic blood pressure, respiratory rate, temperature and mental state. As this simple scoring tool can easily be utilized during the routine bedside observations, it is considered helpful in recognizing patients exhibiting signs of acute deterioration, but also obtaining timely assistance of a skilled clinician. The EWS is mostly coupled with a team (e.g. Critical Care Outreach Service (CCOS), Rapid Response Team (RRT), Patient at Risk Teams (PART)), consisting of experienced medical and/or nursing staff who can provide the support to timely manage the deteriorating patient 32 and thus help improving patient outcomes.
Section snippets
Objectives
In the last decade, several reviews have been carried out concerning critical outreach services using various scoring systems.14, 15, 16, 17, 18 However, most of the studies reviewed the use of a CCOS or an RRT as an efferent limb together with different kinds of early warning systems (afferent limb) rather than the utility of the Early Warning Score and its derived forms.19 Many studies have investigated some form of an EWS system with (or without) a coupled outreach service, finding positive
Search strategy
To identify all relevant publications, we performed systematic searches in the bibliographic databases PubMed, EMBASE.com and The Cochrane Library (via Wiley) from inception to April 8, 2013. Search terms included controlled terms from MeSH in PubMed, EMtree in EMBASE.com as well as free text terms. We used free text terms only in The Cochrane library. Search terms expressing ‘Early Warning Score’ were used in combination with search terms comprising ‘hospital’ and terms for ‘hospital setting’
Mortality
Of the seven included studies,7, 8, 10, 22, 23, 24 six evaluated mortality. Two studies7, 8 found that introduction of an EWS chart after an intensive staff education programme resulted in a significant reduction in overall mortality. Paterson et al.7 found a reduction of in-hospital mortality of 2.8% (p = 0.046), from 5.8% before implementation of EWS to 3.0% after implementation. Moon et al.8 found that the in-hospital mortality significantly reduced from 1.4% to 1.2% (p < 0.0001).
Three studies22
Discussion
In this systematic review we identified seven studies which met our inclusion criteria. These seven studies were all studies investigating patient outcomes before and after implementation of an Early Warning Scores, sometimes coupled with a CCOS. As all included studies were highly heterogeneous in study population, sample sizes and the use of different forms of Early Warning Scores with different alarm thresholds with or without a coupled CCOS, a meta-analysis for different patient subgroups
Conclusion
Despite the fact that much effort has been put in the last decade in developing early warning scoring systems for recognizing patients at risk for deterioration, there still remains a need for improvement in recognition and response. The results of our included studies were mixed, but in general there was a positive trend towards clinical outcomes after the introduction of an EWS system. As the other available scoring systems are either too complex to use or only validated for specific patient
Conflict of interest statement
All authors have disclosed that they do not have any potential conflict of interest.
Acknowledgement
The authors are grateful for the invaluable help of Dr. Louella Vaughan, NWL CLAHRC and Chelsea & Westminster Hospital, Senior Clinical Research Lead and Honorary Consultant Physician, in reviewing our manuscript.
References (32)
- et al.
A comparison of antecedents to cardiac arrests, deaths and emergency intensive care admissions in Australia and New Zealand, and the United Kingdom – the ACADEMIA study
Resuscitation
(2004) - et al.
Impact of a standardized nurse observation protocol including MEWS after Intensive Care Unit discharge
Resuscitation
(2013) - et al.
An eight year audit before and after the introduction of modified early warning score (MEWS) charts, of patients admitted to a tertiary referral intensive care unit after CPR
Resuscitation
(2011) - et al.
Does the use of a track and trigger warning system reduce mortality in trauma patients?
Injury
(2011) - et al.
Predicting cardiac arrest on the wards: a nested case–control study
Chest
(2012) - et al.
The ability of the National Early Warning Score (NEWS) to discriminate patients at risk of early cardiac arrest, unanticipated intensive care unit admission, and death
Resuscitation
(2013) In-hospital cardiac arrest: Is it time for an in-hospital ‘chain of prevention’?
Resuscitation
(2010)- et al.
Duration of life-threatening antecedents prior to intensive care admission
Intensive Care Med
(2002) - et al.
Preventable deaths due to problems in care in English acute hospitals: a retrospective case record review study
BMJ Qual Saf
(2012) National confidential enquiry into patient outcome and death
Cardiac Arrest Procedures: Time to Intervene?
(2012)
In-hospital mortality and morbidity of elderly medical patients can be predicted at admission by the Modified Early Warning Score: a prospective study
Int J Clin Pract
Prediction of in-hospital mortality and length of stay using an early warning scoring system: clinical audit
Clin Med
Validation of a modified Early Warning Score in medical admissions
QJM
Effect of introducing the Modified Early Warning score on clinical outcomes, cardio-pulmonary arrests and intensive care utilisation in acute medical admissions
Anaesthesia
Can physiological variables and early warning scoring systems allow early recognition of the deteriorating surgical patient?
Crit Care Med
The value of Modified Early Warning Score (MEWS) in surgical in-patients: a prospective observational study
Ann R Coll Surg Engl
Cited by (315)
The Effect of Modified Early Warning Score (MEWS) and Nursing Guide Application on Postoperative Patient Outcomes: A Randomized Controlled Study
2024, Journal of Perianesthesia NursingPrediction of acute hypertensive episodes in critically ill patients
2023, Artificial Intelligence in MedicineClinicians’ attitudes towards escalation and management of deteriorating patients: A cross-sectional study
2023, Australian Critical Care
- ☆
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.2014.01.013.