Gating the holes in the Swiss cheese (part I): Expanding professor Reason's model for patient safety

Abstract

Introduction: Although patient safety has improved steadily, harm remains a substantial global challenge. Additionally, safety needs to be ensured not only in hospitals but also across the continuum of care. Better understanding of the complex cognitive factors influencing health care-related decisions and organizational cultures could lead to more rational approaches, and thereby to further improvement.

Hypothesis: A model integrating the concepts underlying Reason's Swiss cheese theory and the cognitive-affective biases plus cascade could advance the understanding of cognitive-affective processes that underlie decisions and organizational cultures across the continuum of care.

Methods: Thematic analysis, qualitative information from several sources being used to support argumentation.

Discussion: Complex covert cognitive phenomena underlie decisions influencing health care. In the integrated model, the Swiss cheese slices represent dynamic cognitive-affective (mental) gates: Reason's successive layers of defence. Like firewalls and antivirus programs, cognitive-affective gates normally allow the passage of rational decisions but block or counter unsounds ones. Gates can be breached (ie, holes created) at one or more levels of organizations, teams, and individuals, by (1) any element of cognitive-affective biases plus (conflicts of interest and cognitive biases being the best studied) and (2) other potential error-provoking factors. Conversely, flawed decisions can be blocked and consequences minimized; for example, by addressing cognitive biases plus and error-provoking factors, and being constantly mindful. Informed shared decision making is a neglected but critical layer of defence (cognitive-affective gate). The integrated model can be custom tailored to specific situations, and the underlying principles applied to all methods for improving safety. The model may also provide a framework for developing and evaluating strategies to optimize organizational cultures and decisions.

Limitations: The concept is abstract, the model is virtual, and the best supportive evidence is qualitative and indirect.

Conclusions: The proposed model may help enhance rational decision making across the continuum of care, thereby improving patient safety globally.

Keywords: cognition; cognitive biases; evidence-based medicine; gate model; healthcare; organizations; patient safety; rational decision making.

Figure 1

Reason's 1997 to 2008 version of the Swiss cheese model (SCM). The original legend for this figure reads as follows: “The Swiss cheese model of how defences, barriers, and safeguards may be penetrated by an accident trajectory.” The figure is from Reason15 and was provided by Mr John Mayor, Chief Production Manager the BMJ, and reproduced with permission from the BMJ Publishing Group Ltd. To our knowledge, Reason has not published any further revisions to the figure

Figure 2

An example to show how the generic Swiss cheese model can be adapted to specific situations—in this case a surgical error. For details please refer to Stein and Heiss.38 “H and P” means history and physical examination. In addition, the figure demonstrates both (1) the barriers (cognitive‐affective gates) to error propagation, ie, gating the holes, and (2) the error catalyzing factors that result in holes or breaching of the cognitive‐affective gates (please see text). Reproduced with permission of Elsevier. Tables 1 and 2 provide complementary information

Figure 3

Simplified representation of the hierarchical influences on patient safety

Figure 4

Simplified representation of the putative cognitive‐affective biases plus cascade. “CoIs” means conflicts of interest. Please see the text for details. Bidirectional arrows represent potential bidirectional reinforcing influences. Solid unidirectional arrows portray predominant unidirectional influences. Grey unidirectional arrow suggests possibility of a direct unidirectional influence. Please see Table 1 for list of error‐catalyzing factors and Table 2 for ways to prevent, minimize, or reverse their consequences. The boxes are convenient envelopes for the text and their relative sizes have no significance. This figure has been substantially revised from figure 3 of Seshia et al25 (publisher: John Wiley & Sons Ltd.) and figure 1 of Seshia et al26 (publisher: BMJ Publishing Group Ltd). Permission from both publishers obtained.

Figure 5

Simplified representation of the proposed integrated cognitive‐affective–gated Swiss cheese model. The middle segment of each “Swiss cheese” layer represents breaching of the cognitive‐affective gate: The holes in the Swiss cheese. Slice A, breach at the level of upstream organizational influences, for example, by (1) unsound decisions made at higher organizational levels or (2) dissemination of erroneous information by those with influence or in positions of authority. Slice B, breach at level of health care professionals, for example, by (1) sleep deprivation or (2) inadequate knowledge. Slice C, breach at the level of patients and caregivers, for example, by (1) suboptimal shared decision making or (2) nonadherence. Please see text for details. Figure 5 integrates the concepts underlying Figures 1, 2, and 4, and information in Tables 1 and 2. The boxes are convenient envelopes for the text, and their relative sizes have no other significance