Evaluation of NEWS2 response thresholds in a retrospective observational study from a UK acute hospital

Abstract

ObjectiveUse of National Early Warning Score 2 (NEWS2) has been mandated in adults admitted to acute hospitals in England. Urgent clinical review is recommended at NEWS2 ≥5. This policy is recognised as requiring ongoing evaluation. We assessed NEWS2 acquisition, alerting at key thresholds and patient outcomes, to understand how response recommendations would affect clinical resource allocation.SettingAdult acute hospital in England.DesignRetrospective observational cohort study.Participants100 362 consecutive admissions between November 2018 and July 2019.OutcomeDeath or admission to intensive care unit within 24 hours of a score.MethodsNEWS2 were assembled as single scores from consecutive 24-hour time frames, (the first NEWS2 termed ‘Index-NEWS2’), or as all scores from the admission (termed All-NEWS2). Scores were excluded when a patient was in intensive care, in the presence of a decision not to attempt cardiopulmonary resuscitation, or on day 1 of elective admission.ResultsA mean of 4.5 NEWS2 were acquired per patient per day. The outcome rate following an Index-NEWS2 was 0.22/100 patient-days. The sensitivity of outcome prediction at Index-NEWS2 ≥5=0.46, and number needed to evaluate (NNE)=52. At this threshold, a mean of 37.6 alerts/100 patient-days would be generated, occurring in 12.3% of patients on any single day. Threshold changes to increase sensitivity by 0.1, would result in a twofold increase in alert rate and 1.5-fold increase in NNE. Overall, NEWS2 classification performance was significantly worse on Index-scores than All-scores (c-statistic=0.78 vs 0.85; p<0.001).ConclusionsThe combination of low event-rate, high alert-rate and low sensitivity, in patients for cardiopulmonary resuscitation, means that at current NEWS2 thresholds, resource demand would be sufficient to meaningfully compete with other pathways to clinical evaluation. In analyses that epitomise in-patient screening, NEWS2 performance suggests a need for re-evaluation of current response recommendations in this population.

Variability and performance of NHS England’s ‘reason to reside’ criteria in predicting hospital discharge in acute hospitals in England: a retrospective, observational cohort study

“…There is significant opportunity for unintended consequences to arise from the implementation of poorly considered clinical decision support, 19 particularly when there is competition for clinical resource. This has been recently discussed for NEWS2, 20 sepsis alerting and COVID-19 virtual wards. 21 R2R has been endorsed and adopted but without validation or consideration of the unintended consequences of its application.…”

The variability and performance of NHS England’s “Reason to Reside” criteria in predicting hospital discharge in acute hospitals in England. An observational study

“…There is significant opportunity for unintended consequences to arise from the implementation of poorly considered clinical decision support (18) , particularly when there is competition for clinical resource. This has been recently discussed for NEWS2 (19) , sepsis alerting and COVID-19 virtual wards (20) . R2R has been endorsed and adopted but without validation or consideration of the unintended consequences of its application.…”

Effect of implementing the NEWS2 escalation protocol in a large acute NHS trust: a retrospective cohort analysis of mortality, workload and ability of early warning score to predict death within 24 hours

“…NNE has been proposed as a method for comparing the ability of early warning scores to accurately predict clinical deterioration in the context of the workload they generate and provide an indirect measure of the cost-efficiency of each alert and of the early warning score employed. In this paper, the method of Kipnis et al 4 was used and is defined as the number of observations that is necessary to respond to in order to pick up one outcome of death within 24 hours 5 6…”