As early as 1998, Vincent and colleagues produced a framework for analysing risk and safety in clinical medicine.124
In this influential article, Vincent refers to Reason's123
model of organisational safety, making a clear distinction between the active failures (slips, lapses, mistakes and violations) of healthcare professionals and the latent organisational failures that provide the conditions in which active failures occur. The past 20 years has seen a proliferation of research using this framework or similar models to understand the causes of patient safety incidents. However, to date, there has been no systematic review of this research and therefore existing frameworks for risk management have a theoretical, but not an empirical, basis.
In this review we identified 95 studies (83 independent datasets) that reported on primary research work with the aim of identifying the factors that contributed to patient safety incidents. A systematic review and analysis of these studies suggests that, despite the availability of frameworks and models that encourage the elicitation of latent and active failures (eg, the AIMS system5
asks people to record any physical environment, equipment or work practice or policy issues that contributed to the incident), the overwhelming majority of contributory factors that were identified in this review (irrespective of hospital setting or methodology) were active failures or individual factors. This tendency to focus on the proximal causes of the incident—although slightly less prevalent in our dataset where the reviewer was a human factors expert—was ubiquitous, with approximately 25% of the contributory factors identified as falling into one of these two domains (active failure or individual factor). In fact, despite claiming to investigate the causes of incidents, some studies did not go much beyond the immediate behaviour, performance or skills of the individual who was ‘responsible’ for the incident.73
Moreover, even when frameworks include systems factors, it is revealing that more attention may be given to the human factors than the systems factors. For example, within AIMS, 33 codes refer to human factors while 21 refer to systems factors. Within the Eindhoven classification (MEDICAL11
) there are nine codes that refer to human failure but only four referring to technical and five referring to organisational failure. This emphasis on human failure, rather than latent failure, is much less profound in the London Protocol and WHO classifications. However, our review found that, to date, these frameworks have been used less frequently in published empirical work that identifies contributory factors.
Our review has informed the construction of a framework of contributory factors which includes 20 key domains and suggests the extent to which these are proximal or distal (active or latent failures). This pictorial representation is based on previously described accident causation models,1
together with the ratings of our expert group. Thus, it should be noted that while the evidence for the domains reflected within the framework is strong, future research is needed to clarify the exact positioning of the domains within the outer rings and the weighting of each domain (perhaps by varying the size of each segment). Although this framework has a greater number of domains than others (eg, the London Protocol includes just seven domains and the WHO classification specifies five main contributing factors) and therefore might be criticised for being more complex, it captures the full range of contributory factors (across different hospital settings) and gives a greater weighting to systems, rather than human failures. Moreover, some interesting findings have arisen from the work reported here, not least the slight differences in the identification of contributory factors for different settings. The fact that this framework differentiates between surgery, where teamwork was frequently identified, and anaesthesia, where equipment and supply issues were more pronounced, highlights its potential to be generalisable across specialties and error types and yet sufficiently detailed to pick up subtle differences between areas of the hospital to allow the targeting of appropriate interventions. Indeed, this framework has the potential to be used in a number of ways to support improvements to patient safety in practice. It can be used to improve the root cause analysis of serious patient safety incidents. For example, it could be used to analyse patient safety incidents to identify the prevalence of contributory factors and to provide feedback on the quality of existing incident analysis processes. The framework could also be used as a basis for the systematic collection of data about the factors contributing to patient safety incidents through the redesign of local and national reporting systems. The quality of the data elicited through existing reporting systems is often poor3
because healthcare professionals who are responsible for reporting errors focus predominantly on the individual and situational factors that are proximal to the error. Without guidance on other factors we may learn little about the organisational interventions that might better support safer practice. The framework may also help clinicians or managers to identify proactively poor safety performance at an organisational level and therefore guide risk management strategies. For example, the framework could be used as the basis for developing a measurement tool for patients to report on the local and organisational factors that impact on their care.
The findings reported here are important but should be treated with caution for two reasons. First, although we identified that active failures, individual factors such as knowledge and experience of the healthcare professionals, communication, and equipment and supplies were the contributory factors most frequently recorded in the literature, this should not be interpreted as reflecting the reality of accident causation. Almost half of the studies included in this review (n=48) did not refer to the use of a theoretical framework to support the identification of contributory factors and only eight made explicit links between theory and the identification of contributory factors. A third of the studies were based on analysing the data from incident reports, data that are often reported to be of poor quality.125
For example, some studies simply referred to active failures (eg, doctor prescribed the wrong drug dose) to explain another active failure or incident, rather than make any attempt to understand the reasons for this behaviour. Typically, incident reporting frameworks rely on those doing the reporting to select probable causes from a given list. This is problematic because the person completing the report may have very little understanding of the factors, active and latent, that contribute to incidents. In addition, when a tick box of contributory factors is available, this might not represent a complete list of possible contributory factors. Second, most staff are not trained in identification of systems failures and may neglect to look further than the proximal cause of the error (eg, a slip or lapse) when attributing causes to the incident. Together, the lack of a theoretical framework, the paucity of data available in many of the articles about the underlying causes of the incidents, and the lack of detail about contributory factors also meant that it was impossible to code approximately 15% of the contributory factors. It is also pertinent that only two of the studies reported here involved patients in defining the nature of a patient safety incident or in identifying causes.77
Therefore, it must be acknowledged that this framework does not encompass a patient perspective on the causes of safety incidents. This is certainly a worthy future endeavour.
While the findings about the prevalence of the contributory factors identified within the studies should be treated with caution, the variety of methods and the reach of the research across a range of hospital specialities provide strong grounds for arguing that this work captures the full range of contributory factors. Moreover, the rigorous process employed for coding the contributory factors and developing the classification of these factors means that the resulting framework has a strong evidence base. This is supported by the extent to which our own framework coincides with existing frameworks in this field.11–14
The framework (see ) explicitly presents contributory factors at a number of different levels (active failures, situational factors, local working conditions, and organisational and external latent factors), which is a welcome addition to the literature. The majority of studies in this review focused on understanding the contributory factors through interviews with frontline staff and their observations and analyses of accidents. These staff may not have a sufficient grasp of the higher-level organisational factors or external policy context that impact on their performance and behaviour. Thus, future research should attempt to further verify the factors in the two outer circles of the framework. Finally, the clear definitions presented within the framework should aid its practical application, and the reliable attribution of contributory factors. In fact, without these definitions the coding task here (see above) was made much more difficult and distinguishing between some domains was problematic (eg, communication and teamwork). Initial pilot work using the framework to categorise contributory factors from 44 serious untoward incident reports within three UK hospital sites has been encouraging, with agreement between two independent assessors at 80%. This compares favourably to published inter-rater reliability of the Eindhoven classification (68%, κ=0.63).126