Elsevier

Resuscitation

Volume 85, Issue 1, January 2014, Pages 109-111
Resuscitation

Short communication
CREWS: Improving specificity whilst maintaining sensitivity of the National Early Warning Score in patients with chronic hypoxaemia

https://doi.org/10.1016/j.resuscitation.2013.08.277Get rights and content

Abstract

Background

The National Early Warning Score (NEWS) is being introduced across the UK, but there are concerns about its specificity in patients with chronic hypoxaemia, such as some patients with COPD. This could lead to frequent clinically insignificant triggers and alarm fatigue.

Aims of study

To investigate whether patients with chronic hypoxaemia trigger excessively with NEWS, and to design a simple variant of NEWS for patients with chronic hypoxaemia: a Chronic Respiratory Early Warning Score (CREWS).

Methods

Data was collected from respiratory wards at two hospitals in North Wales. Components of NEWS and frequency of trigger thresholds being reached were recorded. CREWS was applied retrospectively to patients’ observations.

Results

196 admissions were analysed, including 78 for patients with chronic hypoxaemia. Patients with chronic hypoxaemia frequently exceeded trigger thresholds using NEWS during periods of stability/at discharge. Using CREWS, triggers during stability/at discharge were reduced from 32% of observations to 14% using a trigger threshold of a score greater than 6, and from 50% to 18% using a score greater than 5. All patients with chronic hypoxaemia who died within 30 days still reached CREWS trigger thresholds, and the area under receiver operated curves for NEWS and CREWS was comparable.

Conclusion

CREWS is a simple variant of NEWS for patients with chronic hypoxaemia that could reduce clinically insignificant triggers and alarm fatigue, whilst still identifying the sickest patients.

Introduction

The National Early Warning Score (NEWS),1 an adaptation of the VitalPAC Early Warning Score (ViEWS),2 is being introduced in hospitals across the UK following a recommendation by the Royal College of Physicians.1 NEWS includes three respiratory parameters: respiratory rate, use of supplementary oxygen, and oxygen saturations. Points for oxygen saturations begin to be allocated when levels fall below 96%. Patients with respiratory conditions associated with chronic hypoxaemia such as chronic obstructive pulmonary disease (COPD) often have oxygen saturations below the “normal” range of 94–98%, even when their condition is stable.3 This could lead to persistently high NEWS, resulting in poor specificity of NEWS in this population. Persistent triggers could lead to unnecessary reviews and alarm fatigue,4 where important triggers are not acted on because of the frequency of clinically insignificant triggers – the “crying wolf” phenomenon. Modification of NEWS for patients with chronic respiratory conditions has been suggested as a possible solution,1, 5, 6 though adoption of a standardised evidence-based approach has not occurred to date.

The aim of the present study was to investigate whether patients with respiratory conditions associated with chronic hypoxaemia have persistently high NEWS even during stability, and to design a simple variant of NEWS to improve specificity whilst maintaining sensitivity for such patients; a Chronic Respiratory Early Warning Score (CREWS).

Section snippets

Methods

Data was collected between August and October 2012 on respiratory wards at Ysbyty Gwynedd and Wrexham Maelor Hospital; two NHS District General Hospitals in North Wales, UK. Both wards care for a mixture of respiratory and general medical patients. Data was collected prospectively from patients’ hospital notes, prescription and observations charts using standardised proformas. For patients re-admitted during the study period, only data from the first admission was included. The components of

Results

Two hundred and seventeen admissions were reviewed. Forty-seven patients (22%) were re-admitted to hospital within 30 days of discharge, with twenty-one patients (10%) re-admitted to the same ward within the data collection period; for these patients, only the first admission during the study period was included. Of the 196 included admissions, 98 (50%) were male; 91 (46%) had COPD; and mean age was 70 years (range 19–102, interquartile range 63–82). Ninety-eight patients (50%) had an arterial

Discussion

The present study shows that patients with CH, defined as those with target oxygen saturations of 88–92%, have persistently high NEWS during stability/at discharge. NEWS is based on an early warning score system designed to maximise both sensitivity (the ability to detect patients at risk of dying) and specificity (the minimisation of false alarms) for unselected patients admitted to Medical Admissions Units.1, 2 However, NEWS clearly lacks specificity for CH patients, who make up a significant

Conclusion

CREWS is a simple variant of NEWS for patients with chronic hypoxaemia that could reduce unnecessary triggers and alarm fatigue, whilst still identifying the sickest patients.

Conflict of interest statement

C. Subbe is principal investigator for a study by Philips Healthcare exploring bedside monitoring. The other authors have no relevant conflicts of interest. No external funding was received for this study.

Acknowledgements

We thank Dr. Rhys Jones and Dr. Amanda Skingle for their help with data collection.

References (12)

There are more references available in the full text version of this article.

Cited by (0)

A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2013.08.277.

View full text