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The harm susceptibility model: a method to prioritise risks identified in patient safety reporting systems
  1. Julius Cuong Pham1,
  2. Elizabeth Colantuoni1,2,
  3. Francesca Dominici2,
  4. Andrew Shore2,
  5. Carl Macrae3,
  6. Sara Scobie4,
  7. Martin Fletcher4,
  8. Kevin Cleary4,
  9. Christine A Goeschel1,5,
  10. Peter J Pronovost1
  1. 1Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
  2. 2Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
  3. 3London School of Economics and Political Science, London, UK
  4. 4National Patient Safety Agency, London, UK
  5. 5Johns Hopkins University School of Nursing, Baltimore, Maryland, USA
  1. Correspondence to Mr Julius Pham, 1909 Thames Street, 2nd Floor, Baltimore, MD 21231, USA; jpham3{at}


Background Medical errors are endemic in healthcare. Patient safety reporting systems (PSRSs) have been developed and implemented to identify and reduce medical errors. Although they have succeeded in identifying errors (over 1 million reports in the NHS), there are limited methods by which to analyse this large number of events.

Methods Adapting the safety theory of risk resiliency, the authors developed the Harm Susceptibility Model (HSM) as a method of quantifying the variation in risk of harm within an organisation and the Harm Susceptibility Ratio (HSR) as a statistic to compare and rank harm across trusts or work areas. The HSM was applied to data from 20 trusts reporting events to the National Reporting and Learning System (NRLS) between 2004 and 2006.

Findings A total of 104 674 incident reports from 12 distinct work areas were analysed. Fifty-five per cent of the variation in harm was attributed to differences among trusts, suggesting that HSR would best be used within trusts. Within a specific trust, the HSR ranged from 0.25 to 4.30, with the pharmacy having the highest HSR (4.30, 1.89 to 9.68). The A&E, therapy department and radiology had the highest probability of a high HSR across the majority of trusts.

Interpretation The HSM can be used to analyse a large number of incident reports from PSRSs. It provides a quantifiable way for organisations to identify areas where defences against errors are weak and prioritise limited resources directed at improving patient safety.

  • Patient safety
  • incident reporting
  • national reporting and learning system
  • multilevel analysis
  • statistics

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  • Funding This research was fully funded by the National Health Service, National Patient Safety Agency in the UK.

  • Competing interests CAG has received honoraria from hospitals, healthcare affiliates and government agencies to speak on topics related to quality and patient safety, and has received support from a grant from the National Health Service National Patient Safety Agency. PJP has received honoraria from hospitals and hospital associations to speak on quality and patient safety, and received a grant from the National, Health Service National Patient Safety Agency, and the WHO to study and improve quality of care. The following authors report no conflicts of interest: JCP, EC, FD, AS, CM, MF and KC.

  • Ethics approval Ethics approval was provided by the Johns Hopkins School of Medicine.

  • Provenance and peer review Commissioned; externally peer reviewed.