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The incidence and nature of in-hospital adverse events: a systematic review
  1. E N de Vries1,
  2. M A Ramrattan2,
  3. S M Smorenburg2,
  4. D J Gouma1,
  5. M A Boermeester1
  1. 1
    Department of Surgery, Academic Medical Centre, University of Amsterdam, The Netherlands
  2. 2
    Department of Pharmacy, Academic Medical Centre, University of Amsterdam, The Netherlands
  1. M A Boermeester, Department of Surgery (G4-109.2), Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; m.a.boermeester{at}


Introduction: Adverse events in hospitals constitute a serious problem with grave consequences. Many studies have been conducted to gain an insight into this problem, but a general overview of the data is lacking. We performed a systematic review of the literature on in-hospital adverse events.

Methods: A formal search of Embase, Cochrane and Medline was performed. Studies were reviewed independently for methodology, inclusion and exclusion criteria and endpoints. Primary endpoints were incidence of in-hospital adverse events and percentage of preventability. Secondary endpoints were adverse event outcome and subdivision by provider of care, location and type of event.

Results: Eight studies including a total of 74 485 patient records were selected. The median overall incidence of in-hospital adverse events was 9.2%, with a median percentage of preventability of 43.5%. More than half (56.3%) of patients experienced no or minor disability, whereas 7.4% of events were lethal. Operation- (39.6%) and medication-related (15.1%) events constituted the majority. We present a summary of evidence-based interventions aimed at these categories of events.

Conclusions: Adverse events during hospital admission affect nearly one out of 10 patients. A substantial part of these events are preventable. Since a large proportion of the in-hospital events are operation- or drug-related, interventions aimed at preventing these events have the potential to make a substantial difference.

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  • Funding: This research was funded by the Dutch Organization for Health Research and Development (ZonMw), The Hague, The Netherlands. Patient Safety Program, grant no. 8120.0007. ZonMw had no involvement with the authors’ work.

  • Competing interests: None.

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