3.1 Origins of Efforts to Understand Uptake and Reduce Unwarranted Variation

Concerns about the uptake of research findings and reducing unwarranted variation in practice and outcomes are not new. Spiegelhalter eloquently detailed the long history of enquiry into unwarranted variation in surgical outcomes initiated first in the nineteenth century by Florence Nightingale and then later championed by others, including Ernest Codman.Reference Spiegelhalter¹² Codman advocated systematic follow-up of all patients to understand treatment outcomes, including whether errors were due to lack of ‘technical knowledge or skill’.

In the 1930s, emphasis started to shift towards consideration of variation in the face of what was known to represent effective practice. Glover famously highlighted wide variation in tonsillectomy rates across England and Wales and argued that the only plausible explanation was that ‘it is too often performed without adequate cause, or sufficient regard to the possibility of enlargement being temporary, physiological, or immunological’.Reference Glover¹⁴

This interest was accompanied by the development of methods to improve the quality and efficiency of healthcare, culminating in Donabedian’s paradigm-shifting work on structure, process, and outcome,Reference Donabedian¹⁵ which remains core to much of measurement in health services research. Alongside this work, Lembcke pioneered the use of audit and feedback.Reference Lembcke¹⁶ He demonstrated that by using predetermined criteria, it was possible to collect, compare, and share data on variation in performance with clinicians in ways that could enhance the quality of care delivered. Interest in audit and feedback was rekindled in the 1980s through concerns that simply identifying suboptimal performance was in itself not sufficient to change clinicians’ behaviour.Reference Mitchell and Fowkes^17, Reference Grol, Mokkink and Schellevis¹⁸ The effects of audit and feedback are among the most researched aspects of implementation scienceReference Ivers, Jamtvedt and Flottorp¹⁹ (for further details, see the Element on audit, feedback, and behaviour changeReference Ivers, Audit, Dixon-Woods, Brown and Marjanovic²⁰).

3.2 Diffusion of Innovations

Alongside long-standing concerns about the need to reduce unwarranted variation, the roots of implementation science are deeply embedded within the social sciences, particularly in the literature relating to diffusion of innovations. The history of diffusion research is well described elsewhere,Reference Rogers^21, Reference Greenhalgh, Robert, Bate, Macfarlane and Kyriakidou²² but essentially it offers a theory of how, why, and at what rate new ideas or innovations spread through defined populations and social systems. The influence of the early work of Everett Rogers in rural agriculture is well known, but it is perhaps the work of medical sociologist James Coleman that highlighted the potential of the theory, particularly to those concerned with the production and dissemination of evidence-based clinical guidelines in the late 1980s and early 1990s.

Working in the 1950s, Coleman et al.Reference Coleman, Katz and Menzel²³ investigated the adoption of the then-new antibiotic tetracycline by clinicians in Illinois. They interviewed clinicians about their use of tetracycline 15 months after the drug was introduced, and found that the social networks of participants were strongly associated with uptake.

Rogers reported that later analysis suggested more influence from advertising and pharmaceutical representatives.Reference Rogers²¹ Nevertheless, Coleman’s work surfaced the potential for strategies – opinion leaders, educational outreach, and persuasive communications – that could be used to promote the uptake of research findings or, more pressingly, for codified knowledge in the form of evidence-based clinical guidelines. This became an increasing concern on both sides of the Atlantic.

3.3 Growing Interest in Getting Research Evidence into Practice

The early period of evidence-based medicine focused on producing and synthesising research evidence, on making it more accessible, and on promoting its use in the development of clinical guidelines. This required the creation of methods and supporting evidence infrastructures. In the late 1980s, the RAND Corporation were pioneers of systematic and standardised processes to assess health technologies.Reference Brook, Chassin and Fink²⁴ Also in the USA, the Agency for Health Care Policy and Research was established in 1989 to enhance the quality, appropriateness, and effectiveness of healthcare services.Reference Woolf²⁵ These early iterations of what has become known as health technology assessment is now a mainstay of health systems globally and one of the key building blocks of evidence-based clinical guidelines.

Alongside the systematic codification of knowledge, there was renewed and increasing interest in getting the presented evidence to be adopted and used in practice. In Canada, Lomas et al. were recognising that guidelines alone were unlikely to effect change in actual practice.Reference Lomas, Anderson and Domnick-Pierre^26, Reference Lomas²⁷ In the USA, Soumerai et al. were investigating strategies to improve the prescribing practices of primary care clinicians.Reference Soumerai, McLaughlin and Avorn²⁸ And in Europe, GrolReference Grol²⁹ and Grimshaw and RussellReference Grimshaw and Russell³⁰ were exploring how best to implement clinical guidelines in primary care.

In 1994, the Agency for Health Care Policy and Research convened a conference of experts, including Everett Rogers, to discuss and provide guidance on effective methods of guideline dissemination.Reference Sechrest, Backer, Rogers, Campbell and Grady³¹ At the same time, in the UK these ideas were also being shared with mass audiences in the National Health Service (NHS) via the groundbreaking Effective Health Care series of bulletins – first through Implementing clinical practice guidelines³² in 1994 and then later through Getting evidence into practice.³³ The Effective Health Care bulletins, which were produced by the University of York and began in 1992, predated the creation in 1999 of a national guideline infrastructure in the form of the National Institute for Clinical Excellence (NICE). The bulletins were charged with synthesising and disseminating the best available evidence on selected topics to inform NHS policy and practice.

The 1999 Getting evidence into practice bulletin was one of the first publications to advocate, albeit somewhat naïvely, for theoretically informed implementation.³³ More rigorous and systematic approaches to theory development and application were to follow, most notably led by Michie and Johnston.Reference Michie and Johnston³⁴ Underpinning these approaches was the principle that because evidence-based practice depends on human behaviour, change efforts could be improved by drawing on theories of behaviour change.Reference Michie and Johnston³⁴ Advocacy for and use of theoretical approaches to understand, guide, and evaluate implementation processes was one of the key pre-existing principles from which a new general field of implementation science would emerge. With the launch of the journal Implementation Science in 2006,Reference Eccles and Mittman¹ the field finally had a focal point for its outputs.

3.4 Evolution and Investment in Implementation Studies As a Research Field

Globally, significant investment in research funding and training now supports the field of implementation. The past decade has seen an increase in dedicated, standalone training courses and, most recently, more formal doctoral-level courses. These often adapt and apply methods that are drawn from spheres such as clinical epidemiology, health services research, sociology, and psychology to implementation science questions.Reference Straus, Brouwers and Johnson^35, Reference Proctor and Chambers³⁶ This growth in bespoke training has led in turn to the emergence of researchers who now define themselves as implementation scientists rather than as working within a particular discipline.

The other significant investment has been in research infrastructure. As the potential of implementation science methods has become increasingly recognised, the need to harness the expertise and resources of the field in continuous efforts to improve healthcare systems has also been acknowledged. This recognition has led to the development of new models of research and practice partnerships. In the USA, the Veterans Health Administration has long been at the forefront of efforts to enhance partnered research through its Health Services Research and Development Service and the Quality Enhancement Research Initiative (QUERI).Reference Stetler, Mittman and Francis³⁷ Since 1998, QUERI collaborations have identified service gaps and developed evidence-based best practices, embedding them into routine practice across the Veterans Health Administration system.Reference Atkins, Kilbourne and Shulkin³⁸ The key feature of QUERI has been a strong focus on rigorous comparative effectiveness research and the evaluation of implementation strategies to support uptake and spread. This approach has been mirrored in other geographical settings, most notably in the UK through Collaborations for Leadership in Applied Health Research and Care (CLAHRCs), which were launched in 2008 and funded by the National Institute for Health Research.

CLAHRCs were collaborative partnerships between universities and surrounding health service organisations and were focused on improving patient outcomes through the conduct and application of applied health research. Although CLAHRCs generated a large body of knowledge and learning, the relative lack of national impact on healthcare provision or outcomes has been noted.Reference Kislov, Wilson, Knowles and Boaden³⁹ The policy shift from CLARHCs to Applied Research Collaborations (ARCs) in 2019 suggests efforts to address this. With a clearer focus on high-quality applied health and care research, ARCs may be closer to the QUERI initiative in both form and function.

4.1 Implementation Strategies

Implementation strategies are designed and deployed to bring about changes in healthcare organisations, the behaviour of healthcare professionals, or the use of health services by healthcare recipients.⁴² Put simply, they represent the ‘how to’ element of any change initiative.Reference Proctor, Powell and McMillen⁴³ A large number of implementation strategies have been documented, notably by the Cochrane Effective Practice and Organisation of Care group, and they have long been deemed to be an essential driver for bringing about change in healthcare practice.Reference Lomas^27, Reference Proctor, Powell and McMillen⁴³

The literature has explored the effectiveness of a wide range of strategies, including those targeting the behaviour of individual professionals, those targeting an organisation, and/or those targeting the wider policy context. Table 1 presents a summary of strategies commonly used in healthcare practice, the features that enable their successful implementation, and findings on their effects.Reference Ivers, Jamtvedt and Flottorp^19, Reference Brehaut, Colquhoun and Eva^44–Reference Wells, Tamir and Gray⁵⁶ A more comprehensive classification of implementation strategies has been compiled by the Expert Recommendations for Implementing Change project.Reference Powell, Waltz and Chinman⁵⁷ At first sight, many of the strategies presented in Table 1 look similar to each other, but there are nuanced differences in the approaches taken. For example, one can argue that facilitation is about helping people to change, while opinion leaders influence people to change, and educational outreach can be described as a form of peer-led review of performance.

With small to moderate effects reported across strategies, no single approach appears to be more effective across settings and contexts. Although evidence has accumulated over the past 30 years and synthesis methods have improved, there is much similarity between the summary of findings presented in Table 1 and those of the early reviews of implementation strategies. Those early reviews indicated that while there were no magic bullets for improving the quality of healthcare, a range of interventions were available that, if used appropriately, could lead to improvements in professional practice.Reference Wensing and Grol^58, Reference Oxman, Thomson, Davis and Haynes⁵⁹

This led to suggestions that, despite a growing literature, the science around strategies had stagnated,Reference Ivers, Grimshaw and Jamtvedt⁶⁰ and such concerns have since seen efforts shift away from rudimentary replication studies to a research agenda that focuses on understanding the underlying mechanisms of actionReference Lewis, Boyd and Walsh-Bailey⁶¹ in order to better tailor and optimise interventions to maximise their effects.Reference Wensing^62–Reference Powell, Fernandez and Williams⁶⁴

Although implementation strategies are often presented as discrete or single entities, this is not always the most accurate description. For example, Box 1 shows that an educational outreach strategy, which was deployed to reduce prescribing errors in general practices in England, was actually part of an intervention that was both complex and multifaceted.Reference Avery, Rodgers and Cantrill⁶⁵ In their seminal review of guideline dissemination and implementation strategies, Grimshaw et al. found that nearly three-quarters of included studies were in fact evaluations of interventions deploying multiple strategies.Reference Grimshaw, Thomas and MacLennan⁶⁶

Many early trials of implementation strategies could be considered to have been designed using Martin Eccles’s famous ISLAGIATT maxim: ‘It seemed like a good idea at the time.’ Some strategies suffered from being poorly conceived: little thought was given in the initial stages to the behaviours or processes that needed to be targeted for change to occur, or to whether or not the strategy deployed would (or could) address any underlying factors. Strategies have also often been inconsistently labelled, poorly described, and lacking in sufficient detail to guide their use. This has led to calls for more detailed specification of both the strategies themselves and the behaviours to be targeted in order to ensure greater alignment between intervention components and measured outcomes.Reference Presseau, McCleary and Lorencatto^40, Reference Proctor, Powell and McMillen⁴³ Box 2 provides an overview of two useful frameworks, one for informing strategy selection and intervention design, and one for specifying the behaviour change needed. Both have utility for implementation in practice and provide much-needed guidance on strategy selection.

Attention has also focused on gaining greater understanding of the influence of context where an evidence-based intervention is introduced. A narrow focus on what works, in isolation from the wider economic, political, and social environment within which implementation will occur, is recognised as no longer being sufficient for causal explanation. Rather, implementation is better understood as a critical event in a system that can lead to new understandings, displacement of existing practices, and the evolution of new processes.Reference Hawe, Shiell and Riley⁶⁷ This understanding acknowledges that the context in which implementation takes place is not static but dynamic. Health systems are not fixed organisational structures or entities; rather, they are unfolding and evolutionary, and go through continuous adaptions, so they require constant work to be held together.Reference May, Johnson and Finch⁶⁸ As the two frameworks in Box 2 highlight, an understanding of the context of implementation is an essential prerequisite for strategy selection.

Given all this, there is a case for arguing that the general principles for strategy selection first outlined by Grol nearly 30 years ago – that it should be planned on several levels and that strategies should be directed to the specific barriers to change for specific target groups – still hold true.Reference Grol²⁹

4.2 Theories and Frameworks in Implementation Science

Choice of implementation strategy is likely to be best informed by the nature of the change desired and an informed assessment of how and why a specific strategy is expected to be effective in a given context. Theory provides an essential lens through which we can anticipate, identify, and describe the key features that will influence change. The use of theory helps to clarify the nature of the change required, together with consideration of the wider system, process, and contextual features that need to be addressed if plans for implementation are to be successful. There is now no shortage of implementation frameworks and theories.Reference Tabak, Khoong, Chambers and Brownson^69, Reference Nilsen⁷⁰ (Indeed, one of the less helpful developments in the field over the past decade has been a proliferation of ‘me too’ process models and determinant frameworks, many of which are similarly theoretically grounded, share common antecedents, and apply similar constructs.)

These theories and frameworks can be used to guide the process of translating research into practice, to understand or explain what influences implementation outcomes, or to evaluate implementation efforts generally. Table 2 describes six commonly used theories and frameworks in implementation science. All six have broad utility and can be thought of as evaluation frameworks because they all specify concepts and constructs that may be put into operation and measured. Though a plethora of options exist, this represents a core list through which nearly all implementation issues and questions can be addressed and assessed.

Theory or framework selection can be challenging. As theories and frameworks vary in purpose, complexity, and intended targets, practitioners have reported struggling to identify and select appropriate frameworks to guide implementation in practice.Reference Moore, Rashid, Park, Khan and Straus⁸³ In response to this, practical guides are now available to facilitate the use of frameworks beyond the research setting.Reference Birken, Rohweder and Powell^84–Reference Moullin, Dickson and Stadnick⁸⁷ Box 3 highlights a pragmatic approach to theory selection proposed by Lynch et al.,Reference Lynch, Mudge and Knowles⁸⁵ which seeks to encourage the use of theory to guide implementation in practice.

4.3 Implementation Science in Practice

As this section has illustrated, a large and growing body of evidence on implementation now exists. But, as a research-based discipline, many important messages remain buried in the literature and have yet to disseminate out to routine practice. The shift from CLAHRCs to ARCs (see Section 3.4) is a reflection of growing recognition of the need to better harness the expertise and resources of the field in efforts to improve healthcare.

Models of research and practice partnerships, such as ARCs, are increasingly viewed as integral to the development of learning health systems,Reference Atkins, Kilbourne and Shulkin³⁸ which seek to improve care through a continuous cycle of knowledge production and implementation (see the Element on learning health systemsReference Foley, Horwitz, Dixon-Woods, Brown and Marjanovic⁸⁸). The trailblazer for such initiatives is the QUERI initiative of the US Veterans Health Administration, mentioned in Section 3.4.Reference Atkins, Kilbourne and Shulkin³⁸ A system-wide approach to accelerating the adoption of research-based knowledge, QUERI has long recognised that although there are key differences between doing implementation (i.e. actually putting into practice new evidence-based policies, procedures, or approaches) and undertaking research on implementation, both require infrastructure to ensure capacity and capability.

Box 4 highlights the step-based QUERI framework used to systematically identify and develop evidence-based practices and to embed these into routine practice across the Veterans Health Administration system.Reference Stetler, Mittman and Francis³⁷ As can be seen, this offers an explicit series of steps for first identifying and then addressing practice variations within a health system, as well as simultaneously generating new knowledge and learning. A key feature of QUERI is its strong focus on rigorous comparative effectiveness research, particularly through the evaluation of implementation strategies to support uptake and spread. Since its inception, hundreds of studies have been conducted to inform the organisation and delivery of a wide range of evidence-based services, including mental health, substance abuse services, and diabetes prevention.Reference Atkins, Kilbourne and Shulkin^38, Reference O’Hanlon, Huang and Sloss⁹¹

QUERI can be viewed largely as a research-based initiative, but its strength is that it is fully embedded in a health system and harnesses the principles of co-production in the creation and implementation of research-based knowledge. Implementation efforts are therefore truly a research-practice partnership. As QUERI has developed, focus has increased on the development of research tools and methods to support implementation efforts in practice, and on building system capacity and capability to support primary data collection and foster organisational readiness for change. Infrastructure on this scale not only needs adequate year-on-year funding but also requires a significant commitment to investment in the longer term. It is not surprising, therefore, that the most recent developments in the QUERI framework have focused on ensuring that the impacts of implementation efforts are captured in ways that can facilitate operational understanding of the value of investment on this scale.Reference Braganza and Kilbourne⁹²

5.1 Implementation Science as a Multidisciplinary and Interdisciplinary Field

Implementation science is an inherently multidisciplinary and interdisciplinary field. It draws, as we have mentioned, on theoretical and methodological insights from many disciplines and offers tools for studying implementation at different levels of analysis. However, interdisciplinary thinking is not always apparent in empirical implementation studies. Overall, cross-fertilisation with other social science disciplines remains relatively limited and somewhat unequal. Ideas imported from other fields still tend to be dominated by approaches derived from evidence-based medicine and behavioural psychology, which have been particularly influential in implementation science.Reference Boulton, Sandall and Sevdalis⁹³

Broadly interdisciplinary origins of implementation science, on the one hand, and the predominance of certain disciplinary and epistemological ways of thinking, on the other, make an uneasy combination. This results in a number of tensions. Approaches focusing on group, organisational, and systemic levels of analysis tend to be less utilised than individual educational and psychological approaches. Implementation researchers and practitioners may stubbornly adhere to their preferred methodological orientations, regardless of the nature of the implementation issue or contextual barriers to be addressed. At the same time, the development of some implementation scientists as disciplinary agnostics may cause other difficulties because they may lack in-depth training in core social science disciplines and have a relatively limited methodological and theoretical repertoire on which to draw. As a result, identified implementation problems may not match with the chosen change approaches to address them, and implementation strategies may be poorly tailored to their contexts.Reference Powell, Fernandez and Williams^64, Reference Wensing and Grol⁹⁴

Implementation science could benefit from a broader dialogue with a variety of philosophical and theoretical orientations. This would enable diversification of its epistemological assumptions, conceptual lenses, and methodological approaches.Reference Kislov, Pope, Martin and Wilson⁹⁵ Table 3 provides examples of diverse approaches that could be helpful for addressing implementation questions that have so far been overshadowed by the field’s predominantly positivist agenda. Some of these intellectual traditions, such as critical realism and complexity theory, have already entered the discipline. The adoption of other, less familiar approaches has the potential to lead to the development of novel perspectives on implementation. Engagement with these strands of thinking must, however, take into account their underlying philosophical and disciplinary roots as well as the internal logic and assumptions. Multidisciplinary training programmes for implementation scientists should therefore consider offering in-depth training in at least one core social science discipline, which may require a fine balancing act between multidisciplinary versatility and professional specialisation.

5.2 Implementation Science as a Study of Complex Interventions in Diverse Contexts

One of the recent trends is the increasing complexity and variability of implementation interventions that unfold in diverse and changing contexts. As we described in Section 4, these interventions often comprise multiple, interrelated components and may target several levels within a health system. The traditional focus on what works (i.e. did intervention X lead to outcome Y?) is no longer sufficient for causal explanation (i.e. how, why, and under what circumstances did intervention X lead to outcome Y?).Reference Grimshaw, Ivers and Linklater⁶³ Although process evaluations of implementation interventions are now becoming increasingly routine,Reference May, Cummings and Girling⁷⁷ implementation science has, to date, often offered relatively little understanding as to how different implementation strategies work – that is, the specific mechanisms through which they influence delivery of care.Reference Powell, Fernandez and Williams^64, Reference Lewis, Klasnja and Powell⁹⁷ One possible explanation is that knowledge about processes derived from past interventions is not applied to the development or evaluation of new ones. There is also, speaking more broadly, a problem of one trend replacing another without carrying forward the previous lessons learnt.Reference Powell, Fernandez and Williams^64, Reference Wensing and Grol^94, Reference Lewis, Klasnja and Powell⁹⁷

Another explanation for the current lack of understanding of how different interventions work relates to the dominant patterns of conceptual work in the discipline. Implementation science has been criticised for favouring determinant frameworks and process models. Determinant frameworks, such as the Consolidated Framework for Implementation ResearchReference Damschroder, Aron and Keith⁷¹ and the Theoretical Domains Framework,Reference Cane, O’Connor and Michie⁸⁰ describe types, classes, or domains of factors that act as either barriers or enablers to successful implementation. Process models, such as the knowledge-to-action cycle,Reference Graham, Logan and Harrison⁹⁸ neatly divide an idealised implementation process into a series of phases or stages. Such models and frameworks can helpfully alert researchers to the range of components that should be accounted for in intervention design and evaluation. At the same time, they have a tendency to oversimplify, reducing complex relationships between interventions, implementers, and contexts to prescriptive checklists or stages. Relatively little attention is paid to explicating functional relationships between different determinants, causal mechanisms through which different stages of implementation or contextual variables influence outcomes, or additional mediators and moderators affecting these causal pathways.Reference Powell, Fernandez and Williams⁶⁴

These issues matter for a number of reasons. First, identification of enablers and barriers is only the first step in an implementation journey and is not sufficient for making informed decisions about which implementation strategies should be deployed to address different configurations of determinants. Second, successful implementation is contingent on collective action of multiple implementation actors, such as researchers, managers, and clinicians, who constantly adjust the process of implementation in response to an ever-changing context rather than follow a pre-planned sequence of actions. Finally, some of the best explanations are ‘mechanism-based’,Reference Kislov, Pope, Martin and Wilson⁹⁵ detailing the cogs and wheels of the causal processes through which implementation outcomes are brought about.Reference Hawe, Shiell and Riley^67, Reference Lewis, Klasnja and Powell^97, Reference Hedström and Ylikoski⁹⁹

Box 5 shows how mechanism-based thinking has been applied by different teams to the study of facilitation – an implementation strategy that relies on a designated role (facilitator) encouraging others to reflect upon their current practices to identify gaps in performance, introduce change, enable knowledge sharing, and thus improve outcomes.Reference Kislov, Humphreys and Harvey¹⁰¹ This example highlights the benefits of focusing on relationships and interdependencies between a relatively limited number of elements, such as organisational factors, characteristics of facilitators, and collective processes underpinning facilitation. Mechanism-based explanations presented here shed light on how the interplay between participating entities (i.e. individuals, teams, and organisations), their properties (i.e. roles, expectations, and experiences), and activities (i.e. alignment, prioritisation, engagement, and learning) produces the effect of interest (i.e. successful or unsuccessful facilitation).Reference Hedström and Ylikoski⁹⁹

This example suggests that intervention fidelity should be defined functionally in relation to fit with the underlying causal mechanisms (i.e. what processes does the intervention initiate and how?), rather than compositionally (i.e. what is the composition, dose, and frequency of the intervention?).Reference Harvey, McCormack, Kitson, Lynch and Titchen¹⁰⁴ It also shows that flexible longitudinal designs can be invaluable for exploring causal pathways and uncovering the emergent and dynamic aspects of implementation.

Adopting a mechanism-based approach can also lead to a more nuanced understanding and capturing of implementation outcomes, which otherwise might remain rather crude,Reference Wensing and Grol⁹⁴ as well as to a better integration of formative and summative evaluation findings.Reference Moore, Audrey and Barker^6, Reference Wensing and Grol⁹⁴ Lewis et al. argue that more attention should be paid to proximal implementation outcomes that occur as a direct result of a specific mechanism of action.Reference Lewis, Klasnja and Powell⁹⁷ For instance, the strategy of facilitation acts through the mechanism of enabling group learning on the proximal outcomes of knowledge and skills to influence distal outcomes of clinical behaviour or patient satisfaction. Identification of proximal outcomes can be guided by asking: ‘How will I know if this implementation strategy had an effect via the mechanism that I think it is activating?’

By contrast, distal intervention outcomes – that is, those that an implementation process is ultimately intended to achieve – are not the most immediate elements in the causal pathway.Reference Lewis, Klasnja and Powell⁹⁷ Examples include changes in frequency of certain clinical behaviours or improvements in patients’ symptoms. While such indicators are often extremely informative, they do not necessarily reflect the actual use of research knowledge in healthcare practice for a number of reasons.

• The steps between implementation interventions and distal outcomes may be numerous, making interpretation of causality difficult, especially when causal pathways that make complex interventions work remain unclear.Reference Wensing and Grol⁹⁴

• Taking research knowledge into account when making decisions does not always mean that this knowledge will be implemented in practice.Reference Wensing and Grol⁹⁴ For instance, research evidence can – justifiably – be overridden by individual patient preferences.

• Engagement with new knowledge may lead to subtle and gradual changes in identities, emotions, and discourses that are difficult to measure but can still shape individual behaviours and collective practices.Reference Dickinson and Sullivan¹⁰⁵

One promising avenue for future methodological research could involve design and validation of a new generation of measures that would capture uptake of valuable knowledge, skills, and practices. This may include a range of intermediate indicators closely linked to the mechanisms through which interventions work.Reference Proctor, Silmere and Raghavan² When designing new measures, it is also important to remember that implementation strategies are not without costs and compete with other healthcare activities for finite resources.Reference Hoomans and Severens¹⁰⁶ More economic evaluation would advance the ability to understand which strategies might be suitable for different contexts and whether improvements in implementation are worth the added costs (see the Element on health economicsReference Street, Health economics, Dixon-Woods, Brown and Marjanovic¹⁰⁷). This remains a neglected area of inquiry for the field as whole.Reference Vale, Thomas, MacLennan and Grimshaw^108, Reference Roberts, Healey and Sevdalis¹⁰⁹

5.3 Implementation Science as an Applied Field

Implementation science is an inherently applied field of inquiry. Its knowledge base has been accumulated with an explicit aim of guiding knowledge translation and achieving positive impact on the outcomes of implementation strategies. A significant and increasing body of published research on how to support implementation now exists. However, much of this learning remains ‘locked up’ within the academic community, perversely perpetuating the very same research and practice gap that implementation science has pledged to address. This is not particularly surprising as implementation scientists often operate within institutional structures, which tend to prioritise high-quality academic outputs over generation of pragmatic insights or evidence-based lessons learnt.

Implementation research outputs are mostly written for fellow academics and reflect their preoccupations with methodological rigour, originality, and novelty. Clinicians, managers, and policy-makers (subsequently referred to as ‘practitioners’) are likely to find the following aspects of this development particularly frustrating.

• There has been a massive proliferation of theories, models, and frameworks on implementation and knowledge translation. But many have not been applied and tested in more than one study.Reference Wensing and Grol⁹⁴

• Pressures to generate novel contributions may promote ‘pseudoinnovation’:Reference Walshe¹¹⁰ new implementation models and frameworks often ignore previously published work, reinventing concepts and repackaging what is already known under new labels.Reference Wensing and Grol^94, Reference Walshe¹¹⁰

• Insufficient detail in reporting implementation interventions (e.g. why they were selected, how they were tailored to contextual determinants, what causal pathways they were supposed to activate to achieve outcomes, and how their components were enacted in practice) complicates their practical assessment, replication, and application in new settings.Reference Lewis, Boyd and Walsh-Bailey^61, Reference Powell, Fernandez and Williams⁶⁴

Evaluations of effectiveness (what works) and determinants of change (what elements of context facilitate or hinder implementation), both of which are evident in the mainstream literature, are not necessarily sufficient for addressing practical concerns. What practitioners also want to know is how to address their practical problems by selecting and designing an implementation intervention, how to make this intervention work in practice in the face of numerous obstacles, and how to rapidly evaluate its success. The publication of pragmatic guides helping practitioners to choose between different theories, models, and frameworks to inform their implementation projects is a valuable development in this regard.Reference Lynch, Mudge and Knowles^85, Reference Moullin, Dickson and Stadnick⁸⁷ Elicitation of stakeholders’ programme theories and explication of mechanisms can, in principle, also generate shared understandings and practically applicable knowledge.Reference De Silva, Breuer and Lee¹¹¹ However, if these remain exclusively driven by the agenda of researchers, benefits for practitioners will not necessarily materialise.

At a more fundamental level, many of these issues can be addressed by collaborative research partnerships,Reference Kislov, Wilson, Knowles and Boaden³⁹ implementation laboratories,Reference Ivers and Grimshaw¹¹² and other co-production arrangements that bring together researchers and non-researchers. Much practical, experiential knowledge is collectively generated as part of these increasingly popular collaborative approaches.Reference Reed, Howe, Doyle and Bell¹¹³ However, uptake of co-production in implementation science is not without problems.

First, co-produced, practice-oriented knowledge is rarely captured in codified form and thus may fail to be transferred and applied beyond its original setting. The existing body of work, which tends to target researchers, may therefore need to be complemented by publicly accessible literature with a more pragmatic how-to-do focus. This will require a significant input from practitioners.

Second, despite the rhetoric of improving patient care, the co-design and co-production of implementation studies with patients remains relatively rare, with more attention being paid to collaboration with clinicians and managers within healthcare organisations.Reference Kislov, Wilson, Knowles and Boaden³⁹ Patients, carers, and families impact on the variability and outcomes of interventions, in effect often becoming co-creators of implementation, and can provide unique insights in supporting design and evaluation.Reference O’Hara, Aase and Waring¹¹⁴

Finally, despite significant investment in co-produced forms of working on implementation, many methods for stakeholder involvement are poorly specified, their advantages are often taken for granted, and critical evaluation of their application in practice is missing. Wensing and Grol argue, for instance, that ‘it is unclear how available research evidence and theory is combined with stakeholder involvement, if stakeholders have suggestions that contradict existing knowledge’.Reference Wensing and Grol⁹⁴ More critical and programmatic research into the processes, practices, and impacts of co-produced implementation strategies is therefore a promising area for future development of implementation science as a field. (This is explored further in the Element on co-producing and co-designing.Reference Robert, Locock, Williams, Dixon-Woods, Brown and Marjanovic¹¹⁵)

In summary, multiple barriers to knowledge flows exist between different intellectual traditions, between approaches focusing on determinants, mechanisms, and outcomes of implementation, and between the interests of researchers, practitioners, and service users. Table 4 outlines steps that can be taken to facilitate learning across these boundaries and thus realise the potential of implementation science to contribute to solving real-world healthcare problems in the interest of patients and populations. However, only through joint working that brings together all implementation stakeholders can this learning lead to translating the science of implementation into practice.