Irish National Adverse Events Study

Nurse at station.

This is a landmark patient safety study, jointly carried out by the Royal College of Physicians of Ireland and the Royal College of Surgeons in Ireland.

We wanted to see how common adverse events were in acute Irish hospitals before the establishment of the National Clinical Programmes, and what form they took. We also aimed to identify specific patient safety problems.

Adverse events are unintended injuries or complications that are caused by the management of a patient’s healthcare, rather than by the patient’s underlying disease. Such complications can lead to death, disability or a prolonged hospital stay.

This project will advance the research agenda in quality and patient safety and provide a solid evidence base for service planning and decision-making on patient safety.

The project is funded by the Health Research Board and commenced in 2013.

Doctor with child patient

Why it matters

We all want patients to receive the safest possible healthcare – the management of a patient’s health condition should ease suffering, not lead to additional illness or injury.

The US Institute of Medicine’s 1999 report ‘To err is human’ highlighted the impact of adverse events and emphasised the need to measure and reduce adverse events in all areas of hospital care:

Beyond their cost in human lives, preventable medical errors exact other significant tolls. They have been estimated to result in total costs (including the expense of additional care necessitated by the errors, lost income and household productivity, and disability) of between $17 billion and $29 billion per year in hospitals nationwide. Errors also are costly in terms of loss of trust in the health care system by patients and diminished satisfaction by both patients and health professionals.

"Understanding the types of adverse events that occur, their scope, frequency and preventability is critical for devising policies to reduce harm from medical care."

The Research Priority Setting Working Group of the World Alliance for Patient Safety - 2008

Nurses and doctors in hospital.

Study Methods

Adverse event rates are typically detected by retrospective patient case note reviews.

The international standard for doing this involves a two-stage process: first, nurses screen a random sample of notes using criteria that are potentially indicative of an adverse event.

Physicians then review the notes that were identified by nurses as containing potential adverse events in order to establish occurrence of adverse events and their consequences.

The Irish National Adverse Events Study is using this technique to assess the prevalence and nature of adverse events experienced by patients in Irish acute hospitals.

The patient charts selected for review predate the National Clinical Programmes, which started to operate in 2011. This will allow us, in the future, to evaluate the impact of the Programmes and other quality improvement initiatives on adverse events

"To drive change and improvement you need to know where you stand. This study gives a clear picture of the situation in 2009, prior to the HSE establishing the national clinical programmes in 2010. These programmes offer the opportunity for multidisciplinary and multisite collaboration to improve patient safety."

Dr Philip Crowley

HSE National Director for Quality Improvement


This study was published in BMJ Quality & Safety in February 2016. The main findings were:

  • Numbers: The study found that one-in-eight patients (12.2%) experienced an adverse event as a result of hospital care in 2009. This is broadly in line with international figures where adverse events rates ranged from 3-17% of hospital admissions, depending on how each country defined adverse events.
  • Impact: Almost 7 in 10 of these were rated as having a mild to moderate impact on the patient (ranging from no physical impairment at discharge to moderate impairment but recovery within 6 months), a further 5% caused moderate impairment with disability lasting 6 to 12 months, 10% caused permanent impairment (disability lasting greater than a year), 11% the level of impairment was not recorded at the time of discharge and 7% contributed to death.  Over 70% of the events were considered preventable.
  • Type: The adverse events included: readmission with additional symptoms, hospital acquired infections, delayed diagnosis, and surgical adverse events.
  • Risk: Adverse event risk was higher in admissions for surgical procedures. 
  • Cost: The estimated annual cost of adverse events in 2009 was €194 million.
  • Age: The average age of patients with an adverse event was significantly higher than those without (61.8 years versus 55.4 years).  There was an 18% increase in the risk of an adverse event with every 10 years added to the patient’s age.
  • Gender: No significant difference was reported between men and women in this study.

Meet the Researchers

This project is being led by Professor David Williams, Associate Professor in Geriatric Medicine, Beaumont Hospital and Royal College of Surgeons Ireland (RCSI), with co-investigators Dr David Vaughan, Dr Ann Hickey, Dr Sarah Lett Condell and Ms Gillian Walsh.

Further Reading

Contact Us

If you would like more information about this study, please contact us.

Dr Lucia Prihodova

Manager, Research Department

Tel: +353 1 863 9645

Dr Lucia Prihodova is the Research Manager at the at the Royal College of Physicians of Ireland. Lucia holds a PhD from the Faculty of Medicine at University of Groningen, Netherlands and her research focuses on various aspects of health systems related to work environment, workforce training and wellbeing and patient outcomes.  

RCPI Research

RCPI Research

Tel: +353 1 863 9700