How much of NEWS could be measured by a machine, and would it work?

Abstract

The National Early Warning Score (NEWS)1Royal College of Physicians of London National Early Warning Score (NEWS): standardising the assessment of acute-illness severity in the NHS. Royal College of Physicians, London2012Google Scholar based on VitalpacTM Early Warning Score (ViEWS)2Prytherch D.R. Smith G.B. Schmidt P.E. Featherstone P.I. ViEWS—towards a national early warning score for detecting adult inpatient deterioration.Resuscitation. 2010; 81: 932-937Abstract Full Text Full Text PDF PubMed Scopus (363) Google Scholar has been introduced in hospitals across the UK following a recommendation by the Royal College of Physicians. This aggregate weighted track and trigger system includes mental status, body core temperature, systolic blood pressure, heart rate and three respiratory parameters: breathing rate, use of supplementary oxygen, and oxygen saturations. Currently industry is developing vital sign platforms that should make it possible to continuously monitor more patients both inside and outside hospital. Whilst NEWS is a well validated instrument for the detection of patients likely to die within 24 h it cannot be calculated automatically by a machine as it requires a subjective assessment of mental status and the use of supplementary oxygen must be entered. Mental status and oxygen use are not the only NEWS parameters that machines will find it difficult to monitor. There is still no convenient, reliable and cheap breathing rate monitor on the market, the standard blood pressure cuff is cumbersome and uncomfortable to wear, and core body temperature can only be reliably measured by a rectal probe, or reasonably estimated from either an oral or tympanic thermometer. Core body temperature may well prove to be the most difficult parameter to capture automatically, especially as it is becoming increasingly clear that low rather than high temperatures are more clinically important. An abbreviated version of ViEWS that does not include mental status has been shown to lose very little of its discrimination, albeit in a population that contained very few patients with an altered level of consciousness.3Kellett J. Kim A. Validation of an abbreviated VitalpacTM Early Warning Score (ViEWS) in 75,419 consecutive admissions to a Canadian Regional Hospital.Resuscitation. 2011; 83: 297-302Abstract Full Text Full Text PDF PubMed Scopus (58) Google Scholar Using the same scoring system as NEWS for systolic blood pressure, heart rate, breathing rate and oxygen saturation in a cohort of 43,730 acutely ill medical patients admitted to Thunder Bay Regional Health Sciences Centre, Ontario, Canada the area under the receiver operator characteristic curve (AUROC) for 24 h mortality was 0.86 (95% CI 0.82–0.90) with a Hosmer–Lemeshow goodness-of-fit statistic of p = 0.6. When more parameters are subtracted from the score discrimination is further reduced: the most by the removal of breathing rate or systolic blood pressure, and the least by removing heart rate (Table 1).Table 1Discrimination of different combination of vital signs according to NEWS scoring.AUROCSystolic blood pressure, heart rate, oxygen saturation0.81 (95% CI 0.77–0.85)Heart rate, breathing rate, oxygen saturation0.81 (95% CI 0.77–0.86)Systolic blood pressure, heart rate, breathing rate0.83 (95% CI 0.79–0.88)Systolic blood pressure, breathing rate, oxygen saturation0.85 (95% CI 0.81–0.89) Open table in a new tab Do these findings matter? An early warning score, calculated at a specific point in time, is only a point estimate. The trajectory of the score is probably at least equally important, and perhaps even more so. The combination of parameters to be followed and the weightings they are given may be completely different when continuously monitoring a patient's response to treatment from those that are best for prediction of outcome from a single point estimate. No doubt continuous monitoring technology will give us new insights into the physiology of acute illness, but also create new challenges. No conflicts of interest to declare.