Table 1

Interpretation of the Swiss cheese model of medical error by 85 professionals who claimed to be fairly or very familiar with the model.

Compatibility with Swiss cheese model
 N (%) endorsing statement
 Percent "correct" answers
In your opinion, what does a slice of cheese represent?
          A health care professional
 Sometimes3
 14 (16.5)
 -
          A barrier that protects patients from harm
 yes
 61 (71.8)
 71.8
          A root cause of an error
 no
 9 (10.6)
 89.4
          A procedure that alleviates the consequences of an error
 yes
 14 (16.5)
 16.5
          A defence that prevents the occurrence of an error
 yes
 52 (61.2)
 61.2
In your opinion, what does a hole represent?
          A latent error1
 yes
 28 (32.9)
 32.9
          A loss (in terms of health or money) due to an error
 no
 5 (5.9)
 94.1
          An opportunity for error
 yes
 53 (62.4)
 62.4
          A weakness in defences against error
 yes
 54 (63.5)
 63.5
          An unsafe act
 yes
 17 (20.0)
 20.0
What does the arrow represent?
          The patient's trajectory through the health care system
 no
 29 (34.1)
 65.9
          A transfer of energy that injures a patient
 no
 2 (2.4)
 97.6
          The transformation of a latent error1 into an active error2
 no
 24 (28.2)
 71.8
          The series of events leading to a medical error
 Sometimes4
 51 (60.0)
 -
          The path from hazard to patient harm
 yes
 41 (48.2)
 48.2
How or where is an active error represented on this figure?
          At the base (origin) of the arrow
 no
 10 (11.8)
 88.2
          At the tip of the arrow
 no
 24 (28.2)
 71.8
          As one of the holes
 yes
 26 (30.6)
 30.6
          As the arrow itself
 no
 24 (28.2)
 71.8
          As the alignment of holes
 no
 28 (32.9)
 67.1
How can we make the health care system safer, using the "Swiss cheese" metaphor?
          By adding a slice of cheese
 yes
 27 (31.8)
 31.8
          By removing a slice of cheese
 no
 6 (7.1)
 92.9
          By plugging a hole
 yes
 76 (89.4)
 89.4
          By adding a hole
 no
 1 (1.2)
 98.8
          By making all slices thinner
 no
 6 (7.1)
 92.9

1 Latent error: Failure of system design that increases the probability of harmful events. Loosely equivalent to causal factor or contributing factor.

2 Active error: Error (of commission or omission) committed at the interface between a human and a complex system.

3 A professional whose role is to make the process of care safer may be thought of as a protective barrier

4 This would be true if the error equates with patient harm, as in the case of wrong site surgery

Perneger BMC Health Services Research 2005 5:71   doi:10.1186/1472-6963-5-71