A new tool for hazard analysis and force-field analysis: The Lovebug diagram

Background

Fishbone diagrams (also known as Ishikawa diagrams or cause-and-effect diagrams) have been widely promoted as part of a suite of tools for use in root cause analysis (RCA). The Fishbone diagram is a systems-focused tool for assessing the causes and contributing factors (CCFs) that played a role in an adverse event or near miss.^1–6 This workshop-based tool takes its name from its characteristic shape: As seen in Figure 1, the adverse event is shown on the right; the “spine” of the Fishbone diagram depicts the combined influence of CCFs on that adverse event; boxes labeling different categories of CCFs are connected to the spine via diagonal lines; and the specific incidences of those CCFs are attached horizontally to the appropriate diagonals. Subcauses can be attached to these CCFs, if required. The Fishbone diagram in Figure 1 is used to provide a high-level view of the CCFs related to an incident, but it is worth noting that, where the additional time investment is feasible, the analytical power of the tool is increased when it is used at a more detailed level to address each care/service delivery problem identified. OPEN IN VIEWER

By helping users identify these CCFs, the Fishbone diagram is intended to point out vulnerabilities that can be addressed to make the system safer. In terms of the famous Swiss Cheese model of accident causation, ⁷ it helps users to visualize the holes that lined up to allow harm to propagate through the system.

The example in Figure 1 takes its category headings from the Systems Engineering Initiative for Patient Safety (SEIPS) model of work system and patient safety ⁸ and describes the hypothetical case of a wrong-dose medication error in a community hospital. While the SEIPS model is used here, any number of additional frameworks could be used, such as those proposed by Vincent, ⁹ Rasmussen, ¹⁰ or Runciman et al. ¹¹ As the figure illustrates, potential CCFs related to the technology and tools component or the SEIPS model include the fact that the computerized physician order entry (CPOE) system produces too many alert messages, as well as the fact that it is too easy to override those messages, even when they relate to serious overdoses. The category headings (technology and tools, organization, person, tasks, environment, and process) serve not only as a way of organizing identified CCFs but also as an aid in identifying them.

Treating the category headings as prompts, users can employ the Fishbone diagram as the basis of a structured brainstorming method, similar to other such techniques, including the Structured What-If Technique (SWIFT), ¹² Generating Options for Active Risk Control (GO-ARC) technique, ¹³ or Hazard and Operability Studies (HAZOP).^14,15 Fishbone diagrams can also be used to supplement more tightly-focused risk assessment techniques such as fault tree analysis (FTA). ¹⁶ FTA is quite powerful, but it addresses only those causes that would lead deterministically to an adverse event; it is not capable of assessing contributing factors, which is a key strength of the Fishbone diagram. Other key strengths of the Fishbone diagram include its focus on systems-level causes, rather than individual failings, along with the fact that it is easy to use and that its graphical nature makes it easy to understand at a glance. ²

But the technique suffers from a significant structural weakness. Fishbone diagrams are unidirectional; that is, they depict only the CCFs that may have promoted an adverse event (or near miss). They ignore the other half of the picture: The forces that operated to reduce the likelihood or severity of the adverse event. An emergent strand of research in systems safety highlights the importance of resilience in the form of “error recovery opportunities” ¹⁷ that may enable those involved in an emerging incident to “stop the error cascade.” ¹⁸ More broadly, a full understanding of what went wrong also requires an understanding of what went right. Such an understanding can answer questions like: “Which barriers to harm did not fail?” “Might these robust barriers serve as the foundation for further improvement?” and “Which aspects of the existing system should be retained (or at least changed with care) when redesigning the system to improve safety?”

This paper addresses this weakness by introducing a new approach to mapping the forces influencing an adverse event or near miss; it also describes how the same approach can be used to assess a planned change—including not only risk control action plans but also more general plans like the implementation of a new electronic health record (EHR) system.

Proposed solution: The Lovebug diagram

The Lovebug diagram (Figure 2) extends the Fishbone diagram by mapping the influences both for and against an event occurring. As with the Fishbone diagram, it is named for its resemblance to a shape from nature: in this case, a mating pair of Plecia nearctica, commonly known as Lovebugs. The left side of a Lovebug diagram is the same as a Fishbone diagram and depicts the forces that make an event more likely. The right side of the diagram is laid out as a mirror image of the left and is populated with the forces that make an event less likely. Thus, where the left side serves as a starting point for hazard analysis, the right side serves as a starting point for barrier analysis (albeit without necessarily tying the barriers to discrete cause-consequence pairs, as in traditional barrier analysis).^2,19 OPEN IN VIEWER

Figure 2 expands upon the incident shown in Figure 1. In this scenario, a wrong-dose drug error occurred, but caused only temporary harm because the nurse preparing and administering the medication was monitoring the patient closely out of a concern that the dose might be too high. As a comparison of Figures 1 and 2 demonstrates, the Lovebug diagram presents a far more comprehensive view of the incident than the Fishbone diagram alone. It gives critical information about the error recovery opportunities that could have (or did) ameliorate the harm cased by the initial error. Thus, in addition to informing efforts to reduce the likelihood of the initial error, it also provides a starting point for strengthening or adding barriers to reduce harm if the initial error does occur.

A useful feature of the diagram’s layout is that forces working for and against an event are presented as mirror images. In Figure 2, for instance, it is clear that the error recovery opportunity presented by the overdose alert in the CPOE system was counterbalanced by a low signal-to-noise ratio for alerts, which led the doctor to develop a habit of overriding alerts without reading them closely. Among the risk controls that might arise from this insight would be strengthening this error recovery opportunity by (a) making it more difficult (if not impossible) to override an obvious overdose and (b) reducing the number of extraneous alerts requiring an override.

Other resilience-focused risk control options suggested by the right side of the diagram (and its interaction with the left side) include: training nurses normally on the unit to recognize the normal dosing range for this drug, as well as signs and symptoms of overdose; establishing a formal rapid response team ²⁰ protocol (and ensuring that it can function at night-time staffing levels) to ensure that calling in help from other units works as well next time; implementing a structured communication approach ²¹ to assist nurses in communicating concerns in a way more likely to result in the right response; promotion of “when you have to proceed, but still have doubts, monitor the patient closely” as an important error recovery strategy.

Obviously, the right side of the Lovebug diagram alone is not sufficient; some of the risk controls for this case should also be drawn from the error-promoting side of the diagram (e.g. 24-h hospitalist coverage, and use of the hospitalist as the source for a second opinion when nurses have called for clarification but still have doubts; adoption of unit dosing for high-risk medications, etc.). But it is likely that few of the risk controls suggested by the resilience-promoting side of the diagram would have arisen from an analysis of the error producing side alone. Both error-promoting and resilience-promoting factors must be considered for a complete picture of what happened and how harm can be prevented (or reduced) in the future.

Discussion

The Lovebug diagram retains the strengths and ease of use of both its progenitors; anyone who is familiar with Fishbone diagrams or force-field analysis should be able to adapt to using the Lovebug diagram without any difficulty. This new approach adds value to both approaches, first as extension of Fishbone diagrams that allows for bidirectional, force-field-style analysis, and second a means of imposing a useful structure on force-field analysis (which does not typically benefit from a structured, framework-based approach). It also includes an innovation to improve both Fishbone and Lovebug diagrams: the use of different fonts to reflect stronger and weaker forces. Finally, adding a focus on evidence of good practice may both reduce the negative impact that incident investigations can have on staff morale and also avoid giving an unduly negative impression of the organization to external audiences. ³⁰

Unlike some tools that support structured brainstorming (e.g. the SWIFT ¹² ), the Lovebug diagram also employs its prompts as means of categorizing and organizing the CCFs for action. For this reason, it is probably worth using a well-established framework as the basis for a Fishbone diagram. This paper presented examples using the SEIPS framework ⁸ and the Theory of Organizational Readiness for Change, ²⁵ but, as described earlier, there are many other frameworks available^9–11; the goal should be to select a framework that is well suited to both the problem and the organization within which it is situated. Because frontline workers should be involved in using the Lovebug diagram (and thus the chosen framework), key considerations for selecting a framework should focus not only on the framework’s conceptual robustness but also on the degree to which it can be understood by non-specialists with a practical amount of training.

While the Lovebug diagram represents an advance in existing practice versus Fishbone diagrams and force field analysis, it is worth noting that some research^26,31 and much anecdotal evidence suggests that the use of such systems-focused risk assessment techniques in healthcare RCA may not be as common as practice guidelines^1–5 might imply. Where it is used, the Lovebug diagram should enable users to conduct a more comprehensive analysis of patient safety incidents, but additional research is needed to determine how best to promote the uptake of a truly systems-focused approach to healthcare RCA.

Conclusion

The Lovebug diagram is a novel approach to hazard analysis and the assessment of planned change. A hybrid of the Fishbone diagram and force-field analysis, it depicts the forces that operate both for and against the occurrence of a change from the status quo (whether planned or accidental). Through the use of category headings, it also provides a structured approach to brainstorming and analyzing these forces. While the Lovebug diagram represents a step forward for current practice in the use of both Fishbone diagrams and force-field analysis, overall uptake of systems-focused tools for healthcare RCA may lag behind practice guidelines. Additional research is needed to determine how best to promote the uptake of a truly systems-focused approach to healthcare RCA.