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Understanding the Trigger Tool

3. Resources

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Adverse event

an unintended, unwanted outcome of healthcare which affects the patient. It does not necessarily have to be the result of a mistake or error. In fact, many adverse events are the result of well-intentioned care, which went wrong. Focusing on adverse events helps to spot gaps in the processes of care. It also highlights those aspects of care where staff may have become tolerant of certain known complications of treatments or procedures. This is also known as iatrogenic harm.

Early warning score (EWS)

a simple (physiological) scoring system for assessment of the unwell patient. It uses respiratory rate, oxygen saturation, heart rate, temperature, blood pressure, urine output, and consciousness, to quickly identify patients who are sick or deteriorating. Scores can then be used to trigger appropriate action. The higher the score, the sicker the patient.

Global trigger tool (GTT)

formally the IHI global trigger tool for measuring adverse events. A method for accurately identifying adverse events (harm) and measuring the rate of adverse events over time.

Institute for healthcare improvement (IHI)

is an independent not-for-profit organisation helping to lead the improvement of healthcare throughout the world. Founded in, and based in Cambridge, Massachusetts IHI works to accelerate improvement by building the will for change, cultivating promising concepts for improving patient care, and helping healthcare systems to put those ideas into action.


Online Resource TitleDescription
IHI global trigger tool for measuring adverse events

Griffin, F.A. and Resar, R.K. (2009) (2nd ed.). IHI Innovation Series White Paper. Cambridge, Massachusetts: Institute for Healthcare Improvement.

The Health Foundation

Evidence scan: Global trigger tools (2010).


Reusable Learning Objects – School of Health Sciences, University of Nottingham

NHS Institute for innovation and improvement

Trigger tools (2010).

NHS Improving Quality

1st steps towards quality improvement: a simple guide to improving services (2014).

NHS patient safety

This resource was developed by:

Content authors: Cheryl Crocker, Graham Eyre, Rob Morris

Project developer: Lucrezia Herman

Repurposed by: Amanda Hill, Gill Langmack and Michael Taylor

Acknowledgements: This resource was developed by SONET at the University of Nottingham in cooperation with the NHS Institute for innovation and improvement.

Images of the IHI global trigger tool and the PDSA cycle used with permission.

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