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NIHR Signal Are track and trigger systems linked to rates of in-hospital cardiac arrest?

Published on 9 April 2019

doi: 10.3310/signal-000756

Use of the National Early Warning Score (NEWS) to monitor adults in hospital is associated with reduced risk of having a cardiac arrest while in hospital. Using an electronic rather than paper-based system is also linked to reduced risk.

Many patients who die from a cardiac arrest while in hospital show signs of deterioration beforehand that aren’t identified or acted upon. Several interventions aimed at reducing these avoidable deaths have been introduced in the NHS. These include NEWS, a national track and trigger system introduced in England in 2012. This NIHR-funded study investigated which of these interventions have the most impact

The study was not able to take into account other changes to policy and practice that took place at the same time. This means that the results can only show associations, rather than causation, and more research is needed. Nevertheless, the findings support the use of track and trigger electronic systems.

Share your views on the research.

Why was this study needed?

Acutely ill patients admitted to hospital are at risk of their health deteriorating, which can sometimes lead to in-hospital cardiac arrest. Hospitals deal with about 20,000 arrests in England each year. Approximately 85% of these patients die in hospital. Some of those deaths could be avoided with better monitoring of patients and better responses to signs of deterioration.

In 2000, the Department of Health recommended several interventions that aimed to decrease avoidable deaths and improve standards of care. These included track and trigger systems (see Definitions), nurse-led outreach teams, and structured handover tools. These are all components of a rapid response system.

However, data from the National Cardiac Arrest Audit shows that there is still wide variation in cardiac arrest rates and survival around the country.

This study aimed to investigate which interventions have the most impact on rates and outcomes, by assessing differences in how interventions have been implemented in practice.

What did this study do?

This was a mixed-methods study. Qualitative interviews were undertaken with 60 staff from 13 hospitals, to identify key components of interventions, processes and contextual factors. The results, along with a systematic review, were used to design an organisational survey which was carried out in 171 hospitals. Data from the survey was combined with other national data sources such as clinical activity data. Cross-sectional interrupted time-series, and difference-in-difference analyses were carried out. These examined links between variations in services and in-hospital cardiac arrest rates and survival in 106 hospitals before and after some major service changes were introduced.

The study was limited by relying on survey respondents’ memory when investigating changes over time. It was also unable to take into consideration other policy and practice changes that were taking place at the same time.

What did it find?

  • In-hospital cardiac arrests fell by 6.4% per year and survival increased by 5% per year from October 2009 to March 2015 according to 13,059,865 hospital admissions, with 32,364 patients having 34,202 arrests.
  • National Early Warning Score (NEWS) was introduced in 2012 and was being used by 70% of NHS hospitals by 2015. The use of NEWS was associated with an additional 8.4% decrease in arrests.
  • By 2015, a third of hospitals were using electronic track and trigger systems, rather than paper-based ones.  Switching from paper to electronic systems was associated with an additional 7.6% decrease in arrests.
  • Outreach teams have been increasingly adopted in the NHS since 2000. They have an overarching role of clinical care for critically ill patients on the ward, end-of-life decision-making, and education and quality assurance. However, there are big differences in the way they’ve been implemented in the NHS, in terms of team composition, hours, autonomy, and education or improvement activities. Outreach teams didn’t appear to have an impact on arrests over time.

What does current guidance say on this issue?

NICE’s 2007 guideline on recognising and responding to deterioration in acutely ill adults in hospital says that physiological track and trigger systems should be used to monitor all adult patients in acute hospital settings. It says that trigger thresholds should be set locally and that a graded response strategy to the trigger should be agreed.

The guideline currently does not recommend a specific track and trigger system. However, in February 2019, NICE announced that the guideline will be amended to state that the early warning score NEWS2 has been endorsed by NHS England. The first version, NEWS1, is already endorsed in Scotland and Wales.

What are the implications?

Electronic track and trigger systems, NEWS in particular, are linked to lower in-hospital cardiac arrest rates. However, this study wasn’t able to identify which aspects of the interventions have the most impact, or whether other external factors influenced the associations.

Variation in arrest rates still exists, which may be due to differences in the ways that hospitals have implemented these rapid response systems. This research should help those implementing track and trigger systems and other elements of rapid response systems to better understand the issues so that the number of avoidable deaths in hospital is reduced.

Citation and Funding

Hogan H, Hutchings A, Wulff J et al. Interventions to reduce mortality from in-hospital cardiac arrest: a mixed-methods study. Health Serv Deliv Res. 2019;7(2).

This project was funded by the NIHR Health Services and Delivery Research Programme (project number 12/178/18).

Bibliography

NICE. Acutely ill adults in hospital: recognising and responding to deterioration. CG50. London: National Institute for Health and Care Excellence; 2007.

Why was this study needed?

Acutely ill patients admitted to hospital are at risk of their health deteriorating, which can sometimes lead to in-hospital cardiac arrest. Hospitals deal with about 20,000 arrests in England each year. Approximately 85% of these patients die in hospital. Some of those deaths could be avoided with better monitoring of patients and better responses to signs of deterioration.

In 2000, the Department of Health recommended several interventions that aimed to decrease avoidable deaths and improve standards of care. These included track and trigger systems (see Definitions), nurse-led outreach teams, and structured handover tools. These are all components of a rapid response system.

However, data from the National Cardiac Arrest Audit shows that there is still wide variation in cardiac arrest rates and survival around the country.

This study aimed to investigate which interventions have the most impact on rates and outcomes, by assessing differences in how interventions have been implemented in practice.

What did this study do?

This was a mixed-methods study. Qualitative interviews were undertaken with 60 staff from 13 hospitals, to identify key components of interventions, processes and contextual factors. The results, along with a systematic review, were used to design an organisational survey which was carried out in 171 hospitals. Data from the survey was combined with other national data sources such as clinical activity data. Cross-sectional interrupted time-series, and difference-in-difference analyses were carried out. These examined links between variations in services and in-hospital cardiac arrest rates and survival in 106 hospitals before and after some major service changes were introduced.

The study was limited by relying on survey respondents’ memory when investigating changes over time. It was also unable to take into consideration other policy and practice changes that were taking place at the same time.

What did it find?

  • In-hospital cardiac arrests fell by 6.4% per year and survival increased by 5% per year from October 2009 to March 2015 according to 13,059,865 hospital admissions, with 32,364 patients having 34,202 arrests.
  • National Early Warning Score (NEWS) was introduced in 2012 and was being used by 70% of NHS hospitals by 2015. The use of NEWS was associated with an additional 8.4% decrease in arrests.
  • By 2015, a third of hospitals were using electronic track and trigger systems, rather than paper-based ones.  Switching from paper to electronic systems was associated with an additional 7.6% decrease in arrests.
  • Outreach teams have been increasingly adopted in the NHS since 2000. They have an overarching role of clinical care for critically ill patients on the ward, end-of-life decision-making, and education and quality assurance. However, there are big differences in the way they’ve been implemented in the NHS, in terms of team composition, hours, autonomy, and education or improvement activities. Outreach teams didn’t appear to have an impact on arrests over time.

What does current guidance say on this issue?

NICE’s 2007 guideline on recognising and responding to deterioration in acutely ill adults in hospital says that physiological track and trigger systems should be used to monitor all adult patients in acute hospital settings. It says that trigger thresholds should be set locally and that a graded response strategy to the trigger should be agreed.

The guideline currently does not recommend a specific track and trigger system. However, in February 2019, NICE announced that the guideline will be amended to state that the early warning score NEWS2 has been endorsed by NHS England. The first version, NEWS1, is already endorsed in Scotland and Wales.

What are the implications?

Electronic track and trigger systems, NEWS in particular, are linked to lower in-hospital cardiac arrest rates. However, this study wasn’t able to identify which aspects of the interventions have the most impact, or whether other external factors influenced the associations.

Variation in arrest rates still exists, which may be due to differences in the ways that hospitals have implemented these rapid response systems. This research should help those implementing track and trigger systems and other elements of rapid response systems to better understand the issues so that the number of avoidable deaths in hospital is reduced.

Citation and Funding

Hogan H, Hutchings A, Wulff J et al. Interventions to reduce mortality from in-hospital cardiac arrest: a mixed-methods study. Health Serv Deliv Res. 2019;7(2).

This project was funded by the NIHR Health Services and Delivery Research Programme (project number 12/178/18).

Bibliography

NICE. Acutely ill adults in hospital: recognising and responding to deterioration. CG50. London: National Institute for Health and Care Excellence; 2007.

Interventions to reduce mortality from in-hospital cardiac arrest: a mixed-methods study

Published on 24 January 2019

Hogan H, Hutchings A, Wulff J, Carver C, Holdsworth E, Welch J, Harrison D & Black N.

Health Services and Delivery Research Volume 7 Issue 2 , 2019

Background Unchecked patient deterioration can lead to in-hospital cardiac arrest (IHCA) and avoidable death. The National Cardiac Arrest Audit (NCAA) has found fourfold variation in IHCA rates and survival between English hospitals. Key to reducing IHCA is both the identification of patients at risk of deterioration and prompt response. A range of targeted interventions have been introduced but implementation varies between hospitals. These differences are likely to contribute to the observed variation between and within hospitals over time. Objective To determine how interventions aimed at identification and management of deteriorating patients are associated with IHCA rates and outcomes. Design A mixed-methods study involving a systematic literature review, semistructured interviews with 60 NHS staff, an organisational survey in 171 hospitals and interrupted time series and difference-in-difference analyses (106 hospitals). Setting English hospitals participating in the NCAA audit. Participants NHS staff (approximately 300) and patients (13 million). Interventions Education, track-and-trigger systems (TTSs), standardised handover tools and outreach teams. Main outcome measures IHCA rates, survival and hospital-wide mortality. Data sources NCAA, Hospital Episode Statistics, Office for National Statistics Mortality Statistics. Methods A literature review and qualitative interviews were used to design an organisational survey that determined how interventions have been implemented in practice and across time. Associations between variations in services and IHCA rates and survival were determined using cross-sectional, interrupted time series and difference-in-difference analyses over the index study period (2009/10 to 2014/15). Results Across NCAA hospitals, IHCAs fell by 6.4% per year and survival increased by 5% per year, with hospital mortality decreasing by a similar amount. A national, standard TTS [the National Early Warning Score (NEWS)], introduced in 2012, was adopted by 70% of hospitals by 2015. By 2015, one-third of hospitals had converted from paper-based TTSs to electronic TTSs, and there had been an increase in the number of hospitals with an outreach team and an increase in the number with a team available at all times. The extent of variation in the uses of educational courses and structured handover tools was limited, with 90% of hospitals reporting use of standardised communication tools, such as situation, background, assessment and recommendation, in 2015. Introduction of the NEWS was associated with an additional 8.4% decrease in IHCA rates and, separately, a conversion from paper to electronic TTS use was associated with an additional 7.6% decrease. However, there was no associated change in IHCA survival or hospital mortality. Outreach teams were not associated with a change in IHCA rates, survival or hospital mortality. A sensitivity analysis restricted to ward-based IHCAs did not alter the findings but did identify an association between increased outreach team intensity in 2015 and IHCA survival. Limitations The organisational survey was not able to explore all aspects of the interventions and the contextual factors that influenced them. Changes over time were dependent on respondents’ recall. Conclusions Standardisation of TTSs and introduction of electronic TTSs are associated with a reduction in IHCAs. The apparent lack of impact of outreach teams may reflect their mode of introduction, that their effect is through providing support for implementation of TTS or that the organisation of the response to deterioration is not critical, as long as it is timely. Their role in end-of-life decision-making may account for the observed association with IHCA survival. Future work To assess the potential impact of outreach teams at hospital level and patient level, and to establish which component of the TTS has the greatest effect on outcomes. Funding The National Institute for Health Research Health Services and Delivery Research programme.

Track and trigger systems are a way of recording standard observations (such as heart rate, respiratory rate, blood pressure, oxygen saturation, temperature and level of consciousness) and converting these into a score.

Different scores trigger different responses, ranging from increasing the frequency of observations and alerting the nurse in charge, to an emergency call to a critical care team with advanced airway management and resuscitation skills.

Expert commentary

In-hospital cardiac arrests are, in the majority of cases, predictable and potentially preventable with robust systems which recognise and respond to the deteriorating patient. This enables an early decision about appropriateness of escalation of care. 

From this large analysis of 106 UK hospitals, the two most effective interventions to reduce cardiac arrests appear to be standardising recognition of the deteriorating patient by adoption of NEWS, and electronic monitoring systems to improve reliability. It is less clear which response interventions are the most effective; with no clear evidence favouring outreach teams over ward-based staff. However, this risks oversimplification as typically outreach teams are involved in improving the entire process.

In-hospital cardiac arrests often represent a failure of process. In 2015, less than 30% of these hospitals utilised an electronic system to improve reliability. This must be a catalyst for change.

Dr Dan Beckett, Consultant Acute Physician, Unscheduled Care Clinical Lead, NHS Forth Valley

The commentator declares no conflicting interests