title: The Swiss cheese model of safety incidents: are there holes in the metaphor?
abstract: BACKGROUND
  Reason's Swiss cheese model has become the dominant paradigm for analysing medical errors and patient safety incidents. The aim of this study was to determine if the components of the model are understood in the same way by quality and safety professionals.
  
  
  METHODS
  Survey of a volunteer sample of persons who claimed familiarity with the model, recruited at a conference on quality in health care, and on the internet through quality-related websites. The questionnaire proposed several interpretations of components of the Swiss cheese model: a) slice of cheese, b) hole, c) arrow, d) active error, e) how to make the system safer. Eleven interpretations were compatible with this author's interpretation of the model, 12 were not.
  
  
  RESULTS
  Eighty five respondents stated that they were very or quite familiar with the model. They gave on average 15.3 (SD 2.3, range 10 to 21) "correct" answers out of 23 (66.5%)--significantly more than 11.5 "correct" answers that would expected by chance (p < 0.001). Respondents gave on average 2.4 "correct" answers regarding the slice of cheese (out of 4), 2.7 "correct" answers about holes (out of 5), 2.8 "correct" answers about the arrow (out of 4), 3.3 "correct" answers about the active error (out of 5), and 4.1 "correct" answers about improving safety (out of 5).
  
  
  CONCLUSIONS
  The interpretations of specific features of the Swiss cheese model varied considerably among quality and safety professionals. Reaching consensus about concepts of patient safety requires further work.
authors.affiliation: Institute of Social and Preventive Medicine, University of Geneva, Geneva, Switzerland. thomas.perneger@hcuge.ch
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Perneger
mesh_terms: D000328:Adult; D001291:Attitude of Health Personnel; D032882:Comprehension; D005260:Female; D006801:Humans; D038622:Internationality; D008297:Male; D019300:Medical Errors / Q000145:classification / Q000517:prevention & control; D019365:Metaphor; D008875:Middle Aged; D008962:Models, Theoretical; D011785:Quality Assurance, Health Care; D017751:Safety Management; D012955:Societies, Medical; D011795:Surveys and Questionnaires; D013597:Systems Analysis