Early warning system (medical)

The first recorded EWS was developed by a team in James Paget University Hospital, Norfolk, United Kingdom, and presented at the May 1997 conference of the Intensive Care Society. With the growth in electronic health records, many services have implemented EWS systems in their digital platforms. ==Design and impact==

Early warning systems are typically designed based on statistical analysis of the degree of variation in any given observation (such as vital signs, consciousness or demographics), and corresponding associations with adverse events (such as ICU admission, cardiac arrest, or death). The most common observations utilised in EWSs to predict deterioration is respiratory rate, followed by heart rate, oxygen saturation, temperature, systolic blood pressure, then level of consciousness (either AVPU or GCS). A small number of EWSs include age and sex as predictors of deterioration, as both have associations with in-hospital mortality, however the benefit of including age is negligible and raises significant ethical concerns. Most EWSs are designed to generate a score of up to three for any one given measure. Further delimitation of variation beyond 3 in either direction is believed to not add any additional benefit with the increased complexity. There is however some evidence that certain parameters are better at predicting which patients will die within 24 hours than others. This has led to a call in several countries for the development of a national early warning score that would allow a standardised approach to assessing and responding to deteriorating patients. An example of an early warning system is the VitalPAC Early Warning System (ViEWS), designed in 2010 in response to a recommendation for a national EWS by the UK National Institute for Health and Care Excellence. Some EWSs allow for modifications to the scoring pattern to allow for individual differences and stable pathologies. For example, the Queensland Adult Deterioration Detection System includes "Modified Calling Criteria" that allow senior medical officers to authorise changes to the normal observation ranges for a patient. == Criticism ==

Despite their wide utilisation, there has been little research into the clinical utility of EWSs. Some studies have however found that most EWSs have little clinical effectiveness, potentially due to poor design and implementation. A 2021 study of the Queensland Adult Deterioration Detection System (Q-ADDS) found that while the system was only able to predict approximately half of the patients in a rural or remote hospital who experienced deterioration. Compared to the National Early Warning Score from the UK, Q-ADDS had a higher rate of prediction of deterioration (46.5% Q-ADDS vs 40.8% NEWS) but a higher rate of false-positives (3.2:1 Q-ADDS vs 2.4:1 NEWS). The efficacy of EWSs in improving patient outcomes is also reliant on a number of personal and structural factors. For example, a lack of clinician knowledge of the EWS, incomplete or incorrect vital sign measurement, and the influence of power between nursing and medical staff hinder detection of clinical deterioration. == Early warning system implementations ==

United Kingdom A range of Early Warning Scores have been developed in response to the needs of specific patient types (e.g. PEWS for children) or to support local best practice (NEWS in the UK). In the UK, the Royal College of Physicians developed the National Early Warning Score (NEWS) in 2012 to replace local or regional scores. The NEWS score is the largest national EWS effort to date and has been adopted by some international healthcare services. While many hospitals still use other scores, it has been proposed that all healthcare organisations should use the same score, plus clinical judgement, for diagnosis in the interest of patient safety. Clinical judgment should always be applied as a patient can deteriorate whilst presenting a score of zero. A score of zero does not indicate a stable set of vital signs. Research suggests this patient score can predict worsening condition in care home residents, and that the score could be used in care home settings as well as in hospitals. Australia Standard 8 of the National Safety and Quality Health Service (NSQHS) Standards is Recognising and Responding to Acute Deterioration, which centres on the early detection of deterioration and escalation of care. Action 8.4 of the standard explicitly states that health services are to "graphically document and track changes in agreed observations to detect acute deterioration over time, as appropriate for the patient", and outlines the minimum observations to be taken of all patients. The implementation advise specifically recommends the use of track and trigger charts (also called observation and response charts) to monitor patient physiological status, and encourages the use of digital EWS to improve early detection where properly implemented. The Australian Commission on Safety and Quality in Health Care has also released the National Consensus Statement: Essential elements for recognising and responding to acute physiological deterioration. The statement reiterates the recommendation for track and trigger charts in Australian public and private hospitals, and includes specialist charts that include lactate measurements for sepsis pathway patients. Queensland Queensland Health has developed a range of observation charts used by most public hospitals in the state of Queensland, Australia, designed to meet the requirements of Action 8.4 of the NSQHS Standards. A very small number of Queensland Health facilities have their own EWS charts in use. The family of charts includes: • the Queensland Adult Deterioration Detection System (Q-ADDS), with variations for certain care pathways and rural and remote facilities, • the Queensland Maternity Early Warning Tool (Q-MEWT), which has variations for antenatal and postnatal patients, • the Queensland Children's Early Warning Tool (Q-CEWT), which has variations depending on the specific child's age, • the Queensland Neonatal Early Warning Tool (Q-NEWT). Q-ADDS was developed as a research project by the University of Queensland for Queensland Health to standardise 25 existing observation charts. The chart was designed primarily from The Prince Charles Hospital's observation chart (which was an adaptation of Canberra Hospital's observation chart) and the Children's Early Warning Tool by the Royal Children's Hospital, Brisbane. Q-ADDS has been shown to be able to predict deterioration approximately half of the time, however no other EWS has shown any marked improvement in accuracy over Q-ADDS. ==See also==