The complexity of modern health care interventions

The previous chapter highlighted how reproducing the desired impact of a new health care intervention can be a particular challenge in the case of complex interventions. This chapter explores why complexity poses problems for spreading and replicating interventions.

There is no single definition of a complex health care intervention, though analyses of complexity tend to highlight certain features:

  • the presence of multiple components, either independent or interacting
  • context-embeddedness: complex interventions are built on and interact with the underlying systems, culture and circumstances of the environment in which they are implemented. Indeed, some interventions will be so embedded in their context that it can be hard to distinguish the intervention from its implementation in a specific context.
  • intricacy of causal pathways (that is, the ways in which interventions achieve their effects): these pathways can be multiple and interacting, possibly containing feedback loops, with the effects of some intervention components reinforcing or moderating the effects of others.

Of course, these characteristics are not unrelated. A greater number of intervention components and potential interactions between them will tend to increase the number of ways in which the intervention might supervene upon and interact with the underlying organisational context. And all of this has the potential to increase the complexity of the causal pathways by which the intervention achieves its effects.

The indefinite and potentially contested nature of these characteristics does not always lend itself to drawing hard and fast distinctions about which interventions are complex and which are not. Rather, it might make more sense to think about degrees of complexity. For example, we can imagine a spectrum ranging from simple to highly complex. At one end might be an innovation like a pill, or an intervention that replaces one type of pill with a more effective one. At the other end could be an intervention like a rehabilitation programme, which has multiple components delivered in a range of settings and relies upon a significant degree of patient co-production and behaviour change. In between, one can imagine a range of intervention types that share these characteristics to varying degrees.

Figure 1: Intervention complexity spectrum

Note: Figure 1 illustrates some common types of health care interventions and where they might typically sit on this spectrum. However, we do not intend to suggest that all instances of a particular type of intervention will be of equal complexity.

A failure to consider the full range of issues involved in implementing an intervention could lead one to underestimate its degree of complexity, as illustrated in the case of the Sepsis Six care bundle, described in Box 2. And the more we underestimate the complexity of an intervention, the more likely we are to underestimate the challenges involved in replicating it in new contexts.

Specifically, complex interventions tend to have certain properties (related to the characteristics outlined above) that explain why codifying and replicating them can be so difficult.

First, complex interventions are social, in that they are co-produced and delivered by health care staff, patients and carers. This implicates the attitudes, behaviours, relationships and organisational cultures of those adopting an intervention in its success or failure. Understanding how particular intervention components work may therefore require understanding the social mechanisms that facilitate them, and successful replication may require adopters to re-create these social dynamics in their own setting.

Second, the fact that complex interventions are context-embedded means they are context-sensitive: an intervention’s success will be influenced by aspects of the organisational and wider context in which it is implemented, including the social and relational elements described above. This means it may be necessary for the intervention description to set out which aspects of context influence its effectiveness, and how, in order to aid replication. And to the extent that aspects of organisational context may differ from one location to the next, successful replication may require adaptation of the intervention. As a result, the same intervention may look different in different contexts; for example, when interventions are co-designed with patients, local patient priorities will shape the intervention (and, in the process, challenge standardisation). This, in turn, means that the intervention description will need to capture which components are ‘core’ to making the intervention work and their tolerance to alteration across different settings – what needs to remain invariant versus what can be changed and to what extent.

Third, complex interventions are dynamic, in that the ‘systems’ (people, teams, organisations, etc.) that implement them can learn and self-organise, and the contexts in which they are implemented can throw up new issues requiring a response from those involved., This means that a complex intervention may evolve over time and in unpredictable ways. What is more, its fate may rely heavily on the adopter’s ability to navigate these dynamics and adapt. Indeed, the degree of adaptation and responsiveness required will have consequences for the extent to which the success of the intervention is seen to reside in the specific intervention components themselves versus the agency and capability of the adopter.

Box 2: The complexity of apparently simple interventions: the Scottish national collaborative programme on sepsis

The varying success of an intervention across different contexts can sometimes be a symptom that its underlying complexity has gone unrecognised. One example is the ‘Sepsis Six’ clinical care bundle, which focuses on six key tasks required to treat a patient with sepsis within one hour of diagnosis, including prompt administration of antibiotics and oxygen. Studies have shown significant variation in the effectiveness with which sepsis care bundles are implemented. In light of this, an ethnographic study sought to understand the realities of implementing Sepsis Six on the front line through an investigation of the Scottish national collaborative programme on sepsis, which ran from 2012 to 2014.

Superficial consideration might suggest the Sepsis Six bundle comprises six steps. However, the researchers identified some 48 steps typically required for implementation of the six key tasks. Some required significant input from several staff, making completion within one hour challenging. For example, to effectively administer high flow oxygen, the staff member had to find a doctor and get oxygen prescribed, assess the patient for COPD, gather equipment, wash their hands, explain the reason for the procedure and gain patient consent, administer oxygen, check for comfort and document the procedure.

Across the six key tasks, there were interdependencies inherent in the sequencing of different steps and a lack of synchronisation could arise when staff had to resolve competing demands or manage interruptions. Some steps had social as well as technical dimensions, relying on collaboration between multiple groups of professionals; for instance, nurses in most cases were reliant on doctors to prescribe antibiotics, and on other nurses to check and sign, before they could administer the antibiotics.

The researchers concluded that the challenges of prompt and reliable implementation of the Sepsis Six bundle involve ‘the socio-technical complexity of completing interdependent tasks requiring multiple individuals in different professional groups in a frenetic environment characterised by competing priorities’, and that improving performance ‘requires attention to problems of coordinating tasks, workflow, accountability and expertise’. So, while packaging together different care processes into ‘bundles’ may well be helpful for ensuring consistency, it is clear that effective implementation requires grasping the complexity of the underlying processes and creating working environments that enable them to be delivered.

Analysing complexity

A range of theoretical and practical approaches have evolved for analysing complexity in both health care and health promotion.

One example is realist evaluation, which attempts to understand how an intervention’s outcomes were produced in terms of the underlying mechanisms that drive behaviour and the influence of context on how actors respond. Specifically, realist analysis considers which configurations of context, mechanism and outcome offer the most plausible explanation for the intervention’s effects (here, ‘mechanisms’ are not intervention components but underlying processes triggered by the context that causes or facilitates the intervention’s outcomes).

Realist evaluation is one of a broader set of theory-based approaches that seek to explain how interventions work by elucidating the intervention’s ‘programme theory’ or ‘theory of change’. All interventions are seen as underpinned by a theory – whether the practitioner is aware of it or not – but without making this explicit, it is difficult to fully understand the mechanisms that underpin the intervention’s effectiveness. By uncovering how an intervention works, theory-based approaches can lead to revisions in the innovator’s understanding of their intervention, sometimes in unexpected ways. Box 3 provides an example from the Health Foundation programme Closing the Gap in Patient Safety.

Another type of approach comes from complexity science and complex adaptive systems theory., These disciplines consider an intervention in terms of a system of interdependent agents whose interaction gives rise to emergent, system-wide patterns of behaviour that cannot be reduced solely to the impact of its component parts. Furthermore, such complex systems can self-organise, giving rise to unpredictability, and meaning interventions can evolve.

Different schools of thought handle issues of complexity in contrasting ways. Some view complexity primarily as a property of the intervention and seek to draw relevant background conditions and enabling factors into the conceptualisation of the intervention itself, whereas others tend towards seeing complexity as a feature of the context in which the intervention is embedded. Another point of contrast concerns how and at what level to capture causality: for some, the way to navigate the context dependency of complex interventions is to describe the function of different components within the intervention’s theory of change rather than their specific form; others question whether it is possible to capture causality in this way, because of the difficulty of linking individual components to outcomes, and seek instead to understand the system-level changes triggered by the intervention.,

Whether or not the divisions between the different schools of thought that exist are helpful is debatable. Nevertheless, while we do not seek to play down the philosophical differences between them, in our view they all represent routes for capturing the same underlying features of complex interventions highlighted here: an intervention’s social dimension, how it embeds in its context and how it may evolve over time as those implementing it learn and adapt.

Box 3: Understanding how interventions work: surviving sepsis in Northumbria

Scrutiny of the factors underpinning an intervention’s success can reveal that interventions sometimes have their effects in unexpected ways, requiring those codifying or implementing the intervention to revise their theory of change.

In 2013, Northumbria Healthcare NHS Foundation Trust had a higher than expected mortality rate for people admitted with sepsis, which led to sepsis being identified as a priority for improvement. Supported through the Health Foundation’s programme Closing the Gap in Patient Safety, in 2014 the trust began a quality improvement project to reliably screen patients for sepsis and, where sepsis was identified, to treat them using the Sepsis Six care bundle.

Within 15 months, the project resulted in an increase in patients receiving Sepsis Six within the first hour from fewer than 10% to approximately 60%. Analysis of results from 8,000 screened patients suggest that an estimated 158 lives were saved from reductions in mortality rates.

However, through the project evaluation, the team was surprised to discover that raising staff awareness of the possibility of sepsis through reliable screening ultimately made the greatest contribution to reducing mortality rates; patients assessed using the screening tool were shown to have a 21% lower mortality rate than those for whom the tool had not been used. The subsequent use of Sepsis Six following screening contributed to a further reduction in mortality rates, but not of the same magnitude.

The team also learned about the mechanisms by which the screening tool had this effect. As well as providing a clear pathway for the steps to be taken when sepsis was identified, the tool also promoted team coherence, not least by legitimising nurses’ role in escalating patients and initiating treatment. This was a significant change in practice, as previously nursing staff had simply reported deterioration and awaited instructions from the doctors.

Some common mistakes and misconceptions

The features of complexity considered here pose challenges not just for understanding how an intervention achieves its effects but also for trying to spread it to other settings. The challenges involved can be illustrated by considering some common mistakes and misconceptions that can occur in attempts to codify and replicate interventions.

The first is the belief that the technical components form the ‘hard’ core of an intervention, while the social components are ‘soft’ – that is, discretionary or more open to variation. In fact, the social components may be essential for the intervention to work. This was illustrated in a study of a successful programme to reduce central venous catheter bloodstream infections in intensive care units (ICUs) across Michigan. Some contemporary accounts had viewed the intervention as a simple checklist of five technical components, such as using chlorhexidine for skin preparation and barrier precautions during catheter insertion. However, the study found that the checklist also had an important social function in promoting adherence to these technical practices, because the programme did not simply ask ICUs to use the checklist, but also specified that every catheter insertion should be monitored by a nurse, who would immediately raise concerns if the protocol was not followed. Importantly, this requirement presupposed a restructuring of professional relationships, flattening the traditional hierarchy within the ICU, and it would only work if nurses were able and willing to intervene. In turn, the study found that unwavering support from senior consultants was crucial in enabling nurses to act in this way. Whether one regards such social and relational dynamics as aspects of ‘context’ or of the intervention itself, exposing and understanding them can be essential for effective replication. And this is true not just for interventions that may outwardly appear ‘social’, such as the creation of new teams or ways of working, but also for the use of new technologies or devices; in such cases, the benefits rarely come purely from the technology itself, but rather from the technology being successfully embedded in the human environment of a care process or pathway.

A second possible misconception is to confuse the direct or instrumental effects of intervention components with their expressive or symbolic effects. For example, the study of the Michigan programme cited above found that the requirement for ICUs to create a dedicated trolley containing all the items required for successful catheter insertion not only had instrumental benefits in averting delays but also expressive ones: it signalled the organisation’s commitment to infection control and heightened awareness of the programme. Another example, from the Health Foundation’s Safer Clinical Systems programme, comes from a project which aimed to reduce medication errors on a hospital ward. One component activity, nicknamed the ‘dabber audit’, involved dabbing medication charts with different coloured ink stampers to indicate whether they were correct or needed further action. Originally intended to simplify the data collection process, its visibility meant it came to be regarded as a powerful motivator of behaviour and an educational tool – and as its function mutated, it became possible to see the dabber audit as an intervention in its own right. Sensitivity to the expressive as well as the instrumental functions of an intervention component in a particular context can be important for describing it in a way that supports others to replicate the same effects.

A third possible misconception is a failure to recognise capability-building as an integral part of the intervention. Again, the perception of checklists as a catch-all provides an illustration. While the introduction of surgical safety checklists around the world has sometimes been associated with reductions in surgical complications and mortality, when their use was mandated in Ottawa in 2010, an evaluation found no such improvements, even though compliance with the checklist was high. The researchers noted that, unlike other instances where positive effects of using surgical safety checklists had been observed, the introduction of the checklist in Ottawa had not included team training on how to use it. They suggest a greater effect might have occurred had training been provided.

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These social, context-sensitive and dynamic properties of complex interventions mean that substantial effort and creativity may be required by adopters to translate a new intervention into their own setting and make it work successfully. The next three chapters explore three specific challenges this creates for spread programmes:

  • how to codify complex interventions in a way that can support their implementation in new contexts (Chapter 3)
  • how to incorporate learning from attempts to implement the intervention in new contexts in order to revise and refine it (Chapter 4)
  • how to design spread programmes in ways that build adopters’ commitment and support their work in translating the intervention into their own context (Chapter 5).
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