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Extent, nature and consequences of adverse events: results of a retrospective casenote review in a large NHS hospital
  1. Ali Baba-Akbari Sari1,
  2. Trevor A Sheldon2,
  3. Alison Cracknell3,
  4. Alastair Turnbull4,
  5. Yvonne Dobson2,
  6. Celia Grant2,
  7. William Gray5,
  8. Aileen Richardson2
  1. 1
    Department of Health Management and Economics, School of Public Health, University of Medical Sciences, Tehran, Iran
  2. 2
    Department of Health Sciences, University of York, York, England
  3. 3
    Leeds General Infirmary, Leeds, England
  4. 4
    York Hospital, York, England
  5. 5
    Royal College of Nursing Institute, London, England
  1. Professor Trevor A Sheldon, Department of Health Sciences, University of York, Seebohm Rowntree Building, Heslington, York YO10 5DD, England; tas5{at}


Objectives: To estimate the extent, nature and consequences of adverse events in a large National Health Service (NHS) hospital, and to evaluate the reliability of a two-stage casenote review method in identifying adverse events.

Design: A two-stage structured retrospective patient casenote review.

Setting: A large NHS hospital in England.

Population: A random sample of 1006 hospital admissions between January and May 2004: surgery (n = 311), general medicine (n = 251), elderly (n = 184), orthopaedics (n = 131), urology (n = 61) and three other specialties (n = 68).

Main outcome measures: Proportion of admissions with adverse events, the proportion of preventable adverse events, and the types and consequences of adverse events.

Results: 8.7% (n = 87) of the 1006 admissions had at least one adverse event (95% CI 7.0% to 10.4%), of which 31% (n = 27) were preventable. 15% of adverse events led to impairment or disability which lasted more than 6 months and another 10% contributed to patient death. Adverse events led to a mean increased length of stay of 8 days (95% CI 6.5 to 9). The sensitivity of the screening criteria in identifying adverse events was 92% (95% CI 87% to 96%) and the specificity was 62% (95% CI 53% to 71%). Inter-rater reliability for determination of adverse events was good (κ = 0.64), but for the assessment of preventability it was only moderate (κ = 0.44).

Conclusion: This study confirms that adverse events are common, serious and potentially preventable source of harm to patients in NHS hospitals. The accuracy and reliability of a structured two-stage casenote review in identifying adverse events in the UK was confirmed.

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  • Ethics approval: reference number: 04/Q1108/7.

  • Funding: ABS was supported by a scholarship from the Iranian Ministry of Health and carried out this work while a studying for a PhD at the University of York.