Toward the sustainability of health care innovations to “transform our world”: current status and the road ahead

Abstract

ABSTRACT

Inadequate sustainability of health care innovations or evidence-based interventions has led to calls from policymakers, researchers, and funders for research on how sustainability can be optimized to avoid research waste. In this discussion paper, we argue that research on health care innovation sustainability needs to be advanced. We critically examine the literature on the concept of sustainability and propose that research should address the fundamental question: How can we advance knowledge on health care innovation sustainability? We provide examples of important work undertaken in the field of implementation science, including definitions and conceptualizations of sustainability. We also highlight theories, models, and frameworks that have been proposed to inform sustainability research and guide how to plan for sustainability. Our analysis of the literature reveals a growing interest in the sustainability of health care innovations but also confirms that implementation science has yet to put sustainability at the center of its research endeavors. To assist this shift, we identify priority research gaps and use the United Nations 2030 Agenda for Sustainable Development as a road map for an implementation science research agenda to drive health care innovation sustainability. We propose three new research directions that, overall, aim for “better health for all, leaving no one behind.” These directions include: (1) advancing substantive research on sustainability while avoiding duplication; (2) identifying barriers, facilitators, and strategies to sustain engagement with multiple partners; and (3) advancing methods and tools to support monitoring, evaluation, and revision of strategies over time.

Spanish abstract:

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What is known about the topic?

• Sustainability of health care innovations is paramount to ensure long-term, high-quality patient care and optimize health system impact.

• The two foundational challenges to the study of sustainability and interpretation of relevant literature include the numerous conceptualizations and definitions of the phenomenon and the related but not entirely equivalent terms that have been used in the literature to refer to sustainability.

• There is a significant number of implementation science theories, models, and frameworks that can be used to inform sustainability research and support sustainability-oriented plans across various health care settings and contexts.

What does this paper add?

• Despite the increasing concern and importance accorded to sustainability research in implementation science, most of the efforts remain at a conceptual level, with sustainability and related concepts appearing more often in conceptual papers than in empirical articles.

• We advocate the advancement of sustainability research and practice and propose an implementation science research agenda that aligns with the UN 2030 Sustainable Development Goals.

• In particular, we suggest three new directions for advancing sustainability research: (1) advancing substantive research on sustainability while avoiding duplication; (2) identifying barriers, facilitators, and strategies to sustain engagement with multiple partners; and (3) advancing methods and tools to support monitoring, evaluation, and revision of strategies over time.

INTRODUCTION

Among the most pressing challenges confronting our world today (e.g., poverty, inequality, climate change, environmental degradation), the health and well-being of populations is of central importance and consumes significant resources.¹ Globally, an estimated quarter of a trillion US dollars is consumed every year in both the public and private sectors on biomedical, clinical, and health services research.^2,3 Unfortunately, evidence suggests that a high proportion of this staggering sum is avoidably wasted.^2,4 For instance, only a fragment of relevant research findings translates into measurable, sustainable changes,^5,6 and it often takes years for new research evidence to influence public policies and improve health care, with estimates ranging up to 28 years.⁷

A primary goal—if not the raison d’être—of implementation science (IS) or knowledge translation (both referred to as IS hereafter) is to produce research knowledge that supports practice change to improve the quality and delivery of health care. As IS has grown, researchers have advanced from examining barriers and facilitators that influence uptake of health care innovations to investigating strategies to improve uptake by adopters. While initial implementation efforts have been the subject of an increasing amount of research in the past, there is a dearth of research providing insights into what happens beyond that point. Sustainability of health care innovations¹ is paramount to ensure long-term, high-quality patient care and consistently optimize the impact on the health system.^8–10 Moreover, failure to sustain evidence-based changes or innovations to practice means that expected improvements in care are short-lived; scaling up and diffusion of health care innovations are unlikely; and losses are incurred on research investments, often made with public funds.¹¹ However, despite the critical importance of the topic, Proctor et al.⁶ argued in 2015 that sustainability of health care innovations is “one of the most significant translational research problems of our time.”

So, where has the field evolved since then? Although researchers have increasingly moved beyond initial implementation to look at longer-term outcomes,¹² more work is needed. The sustainability of health care innovations represents an important, consequential area of advancement for IS scholars. There is a timely opportunity to conduct research that can inform health systems and policy debates and to become active in the global discourse on transforming health care for “better health for all, leaving no one behind”.¹ Therefore, the main objectives of this discussion paper are to provide an overview of the current state of the literature on health care innovation sustainability and to offer a road map for future research that seeks to advance this important area, using the United Nations (UN) 2030 Agenda for Sustainable Development¹ as a framework. In section 2, we first explore how sustainability has been conceptualized and present a range of comprehensive definitions that have been proposed. Then, we survey the landscape of IS theories, models, and frameworks (TMFs) that can be used to promote meaningful research on health care innovation sustainability. We conclude section 2 with a brief overview of existing empirical research on the sustainability of health care innovations, followed by a summary of our analysis and interpretation of the literature to identify important, unanswered research questions that warrant further scientific attention. In section 3, we build on section 2, using the UN 2030 Agenda for Sustainable Development¹ as a framework to propose new directions for advancing sustainability research and suggest appropriate methods/approaches to address them.

OVERVIEW OF EXISTING LITERATURE

There is growing literature on health care innovation sustainability^6,8–48; however, a knowledge synthesis of all published work in IS is beyond the scope of this paper. We draw on existing knowledge scattered across various research areas within IS to conduct an analysis of the literature on health care innovation sustainability. Specifically, we identified relevant literature though searches of electronic databases, prior knowledge syntheses, and consultation with IS experts. Search terms included combinations of IS terms, with a focus on sustainability (e.g., sustainability, sustained, sustainment, maintenance, integration) as well as health-related terms (e.g., health innovations, health policies, public health). The PubMed and PsycINFO databases were searched for articles published in English in the last 5 years in publications in the field of IS. Hand searches were conducted of IS TMFs knowledge syntheses,^49,50 as well as knowledge syntheses exploring sustainability and how it relates to health care innovations.^9,11,13–32 IS experts reviewed the list, which is by no means complete, of included knowledge syntheses, definitions of sustainability, and IS TMFs to ensure the completeness and relevance of the articles selected for this analysis.

In this section, we summarize several representative definitions and conceptualizations of sustainability in the field of IS and refer to the existing literature, as appropriate. We then explore some of the IS TMFs that have been proposed to guide the study or evaluation of sustainability and consider their implications for sustainability research and practice. We conclude with a discussion summarizing our analysis and interpretation of the literature on health care innovation sustainability to highlight important research gaps. Our analysis reveals that sustainability research has largely focused on two topics: improving clarity in sustainability terminology and concepts by developing definitions and conceptualizations of sustainability that apply to the field of IS (i.e., the process of breaking and converting research ideas into simplified, common meanings or representations of real-world situations or phenomena); and understanding the phenomenon of sustainability from an IS perspective by developing and proposing TMFs.

Exploring the concept of sustainability: terminology, definitions, and conceptualizations

The diversity and fragmentation of the literature on the sustainability of health care innovations have been robustly documented in prior knowledge syntheses.^13–24 As such, two of the foundational challenges to the study of sustainability and the interpretation of relevant literature include the numerous conceptualizations and definitions of the phenomenon^6,17,44 and the related but not entirely equivalent terms that have been used by researchers in differing fields.^20,51 Hence, it is possible that the same underlying concept (i.e., sustainability) is described using different terms (synonymy) or defined in different ways using similar key constructs (polysemy), which makes it challenging for those using the relevant literature or advancing sustainability science. For example, Tricco and colleagues¹⁹ found that only 13% (n = 8/62) of the studies included in their scoping review of interventions in health care decision-making related to chronic disease management provided a clear definition of sustainability. Mixed results of sustained evidence-based interventions in various other settings have been attributed to a limited theoretical basis.⁵² One explanation for the lack of referenced definitions could be that selecting a definition can be difficult, given that commonly used definitions of sustainability describe different constructs: sustainability can refer to the sustained delivery of a clinical intervention and implementation strategies or the maintenance of individual changes in behavior and health benefits; and it can be assessed at multiple levels (e.g., patient, provider, organization, community, system).

In the IS literature, researchers use a range of terms to describe sustainability, sometimes interchangeably; the most frequently used terms include sustain, sustainment and sustained, durability, maintain and maintenance, continuity and continuation, and long-term or follow-up implementation.^26,38,44,51 However, a multitude of other terms have also been used, such as adhere,¹⁹ penetration,^51,53 institutionalization,⁵⁴ routinization,^42,43 normalization,⁵⁵ integration,⁵⁶ capacity-building,³⁷ and, recently, evolvability³¹ and scalability.⁴⁹ These related but distinct terms largely relate to the continued enactment of processes, practices, or work routines that are conveyed and learned through an intervention/program so it becomes integrated into existing systems¹⁴; however, their operationalization differs. There has also been debate on the distinction between the concepts of sustainability and sustainment, with some authors arguing that sustainment is an outcome of a sustainability effort.^20,57 Chambers¹⁰ developed a commonly used description that highlights this distinction, referring to sustainability as the “characteristics of the intervention that may lend itself to be used over time” and to sustainment as “whether the intervention sustained over time—as an outcome.” Another group of researchers described sustainability as “sustained benefits,” and sustainment as “sustained use”.⁵⁸ Work in this field has also acknowledged useful distinctions between sustainability and routinization (i.e., individual-level change), institutionalization (i.e., organization- and system-level change), and scalability (e.g., “deliberate efforts to increase the impact of successfully tested health innovations so as to benefit more people”),⁵⁹ and it has also distinguished maintenance of behavior change (i.e., whether the implementer is following the recommendations of the evidence-based program, practice, or guideline) from maintaining outcomes (e.g., expected long-term benefits), which are all considered separate constructs.¹⁸

Similarly, there are various definitions of sustainability used in the IS field.^{6,11,17,18,38,48} For example, sustainability has been defined as “the persistence of routinization or institutionalization of the initial innovation,” “the continued evolution or adaptation of the innovation over time,” “the endurance of innovation-related benefits for individuals and/or systems,” and different amalgams of these characteristics.^14,18,29 Similarly, sustainability was conceptualized as the process or ongoing stage by which an innovation becomes integrated into existing systems,^16,39 an outcome in which the innovation is sustained after initial implementation or after funding ends,⁶⁰ or a combination of both.³¹ A concept analysis completed by Fleiszer et al.¹⁴ proposed a broad conceptualization of sustainability consisting of three characteristics: benefits, routinization or institutionalization, and development. Their conceptualization also suggested that sustainability of health care innovations is influenced by a variety of conditions or factors that are related to innovation, context, leadership, and processes.¹⁴ Similarly, other scholars have approached sustainability from a systemic or ecological perspective, whereby the innovation and the environment were perceived as being interrelated.^11,22,47

Adding further confusion, imprecise definitions have been frequently used; for example, sustainability has been defined as “a further stage in the translation or dissemination of research-based interventions into practice,”⁴⁴ viewing sustainability as an extension of initial implementation without considering exactly what is being sustained (e.g., clinical intervention, implementation intervention, outcomes) and that it should be considered from implementation outset. Additionally, some studies have defined different levels of sustainability based on time.²³ For example, a review by Roussos and Fawcett⁶¹ suggested that implemented public health programs can influence health behaviors if they are sustained for at least 2 to 5 years; however, to affect population-level outcomes, these efforts must be sustained for at least 10 to 20 years. In contrast, Scheirer and Dearing⁴⁴ delineated levels of sustainability into “processes” in the early stages of a health program (e.g., project planning and adoption, organizational support, financial strategies) that then affect “activities and outcomes” beyond the initial implementation. Likewise, Greenbert et al.³⁶ discussed that “early sustainability” refers to the continuation of effective activities and creating structures for operations and activities, whereas the “final phase” involves strengthening collaborative functioning, maintaining program implementation quality, and developing local funds and support. Within the literature focusing on measures of sustainability and sustainability determinants (i.e., what influences sustainability), the definitions are similarly disparate.^{19,21,38,62,63}Table 1 reflects this conceptual diversity and highlights how the definitions and conceptualizations of sustainability identified within the IS literature have evolved.

Table 1.

Comparisons of sustainability definitions and conceptualizations in IS, listed chronologically by year of publication

Author(s)	Sustainability definition or conceptualization	Corresponding framework/model/theory and/or measurement tool, with additional information
Brinkerhoff et al., 199264	“It is the ability of an organization to produce outputs of sufficient value so that it acquires enough inputs to continue production at a steady or growing rate.”	- Generic framework for understanding institutional sustainability in development.
Shediac-Rizkallah & Bone, 199847	“(1) [M]aintenance of a program's initial health benefits, (2) institutionalization of the program in a setting or community, and (3) capacity building in the recipient setting or community.”	- Refers to three operational indicators of sustainability. - Consistent with institutional theories of organizations, which postulate that “the final stage of innovation requires the institutionalization of the new practice so that it becomes a working part of the organization.”10
Glasgow et al., 199965	“The extent to which innovations become a relatively stable, enduring part of the behavioral repertoire of an individual (or organization or community).”	- Refers to the “Maintenance” dimension in the RE-AIM framework, which measures “the extent to which a program is sustained over time.” - “Maintenance” in RE-AIM has been operationalized at both individual (i.e., long-term maintenance of behavior change) and organization–community (i.e., when a change is institutionalized, that is, “the extent to which a practice, program or policy becomes routine and part of the everyday culture and norms of an organization”) levels.
USAID, 199966	“The ability of activities to continue appropriate to the local context after withdrawal of external funding.”	- Information pamphlet discussing how to maximize the impact and sustainability of USAID sponsored programs Europe and Eurasia.
Greenhalgh et al., 200467	“Sustainability of organizational innovations can be thought of as the point at which new ways of working become the norm and the underlying systems and ways of working become transformed in support.”	- Developed based on a systematic review of the diffusion of service innovations, which synthesizes evidence from 495 sources including empirical studies, and methodological and theoretical articles.
Johnson et al., 200437	“The process of ensuring an adaptive prevention system and a sustainable innovation that can be integrated into ongoing operations to benefit diverse stakeholders.”	- Informed definition of sustainability and an associated planning model for sustaining prevention innovations within organizational, community, and state systems. - Provides a conceptual and practical understanding of sustainability and tools to assist in implementing the planning model. - The model assumes a five-step process (i.e., assessment, development, implementation, evaluation, and reassessment/modification) and addresses factors known to inhibit efforts to sustain an innovation.
Sarriot et al., 200462	“A contribution to the development of conditions enabling individuals, communities, and local organizations to express their potential, improve local functionality, develop mutual relationships of support and accountability, and decrease dependency on insecure resources (financial, human, technical, informational), in order for local stakeholders to negotiate their respective roles in the pursuit of health and development, beyond a project intervention.”	- Developed in the context of non-governmental organization child survival projects. - Used to develop the CSSA methodological approach, a framework and process to map progress toward sustainable child health from the community level and upward.
Rogers, 200568	“[T]he degree to which an innovation continues to be used after initial efforts to secure adoption are completed.”	- Diffusion of Innovation Theory.
Scheirer, 200522	“(a) [C]ontinuing to deliver beneficial services (outcomes) to clients (an individual level of analysis); (b) maintaining the program and/or its activities in an identifiable form, even if modified (an organizational level of analysis); and (c) maintaining the capacity of a community to deliver program activities after an initial program created a community coalition or similar structure (community level of analysis).”	- Refers to three definitional measures of sustainability, which are derived from Shediac-Rizkallah and Bone's conceptualization.47 - Review and synthesis of 19 empirical studies on the sustainability of American and Canadian health-related programs.
Sridharan et al., 200769	“[O]ur conceptualization of sustainability was on the inter-organizational relationships that might serve as a basis of the collaborative problem-solving capacity.”	- Analysis of the sustainability dimension in 5-year strategic plans of comprehensive community initiatives.
Feldstein & Glasgow, 200863	“The goal of program and performance maintenance”	- PRISM, a comprehensive model for translating research into practice. - Evaluates how the health care program or intervention interacts with the recipients to influence program adoption, implementation, maintenance, reach, and effectiveness. - Focuses on implementation and sustainability infrastructure, which includes performance data, dedicated teams, adopter training and support, relationship, and communication with adopters, adaptable protocols and procedures, facilitation of sharing of best practices, and plan for sustainability.
Gruen et al., 200815	“The simplest definition of sustainability is the ‘capability of being maintained at a certain rate or level’.”	- Systematic review of conceptual frameworks and empirical studies on the sustainability health programs.
Rabin et al., 200851	“[T]he extent to which an evidence-based intervention can deliver its intended benefits over an extended period of time after external support from the donor agency is terminated.”	- Glossary of IS terms. - Based on Scheirer's22 conceptualization.
Sarriot et al., 200870	“Sustainability is a process that advances conditions that enable individuals, communities, and local organizations to improve their functionality, develop mutual relationships of support and accountability, and decrease dependency on insecure resources (institutional, technical, financial). Sustainability enables these local stakeholders play their respective roles effectively, thus maintaining gains in health and development beyond the project period.”	- SHOUT Group Sustainability Framework and Practical Guide to Sustainability Planning and Measurement in Community-Oriented Health Programming.
Scheirer, Hartling & Hagerman, 200845	“[M]aintaining program activities, continuing to serve substantial numbers of clients, building and sustaining collaborative structures, and maintaining attention to the ideas underlying the projects by disseminating them to others.”	- Refers to four definitions of sustainability measures.
Maher et al., 201071	“[W]hen new ways of working and improved outcomes become the norm.”	- NHS Sustainability Model and Guide.
Aarons et al., 201172	“We use the term sustainment to denote the continued use of an innovation in practice.”	- The EPIS Framework, a multi-level, four-phase conceptual framework of the implementation process.
Scheirer & Dearing, 201144	“[T]he continued use of program components and activities for the continued achievement of desirable program and population outcomes.”	- Conceptual framework for sustainability of public health programs, which envisions sustainability “in relation to previous stages in an overall programmatic life cycle of intervention development, adoption, implementation (with potential iterative adaptations), and sustainability.”
Slaghuis et al., 201156	“[A] dynamic process in which actors in a target work practice develop and/or adapt the organizational routine to a new work.”	- Part of the development of a framework and measurement instrument for sustainability of work practices in long-term care. - Focuses on the concepts of routinization and institutionalization.
Wiltsey Stirman et al., 201220	- “(1) [W]hether, and to what extent, the core elements (the elements mostly closely associated with desired health benefits) are maintained; (2) the extent to which desired health benefits are maintained and improved upon over time after initial funding or supports have been withdrawn; (3) the extent, nature, and impact of modifications to the core and adaptable/peripheral elements of the program or innovation; (4) continued capacity to function at the required level to maintain the desired benefits.” - “A program or intervention's impact may be considered sustained if desired health benefits remain at or above the level achieved during implementation and this increase can be attributed to continuation of the program.” - “A program or intervention may be considered to be sustained at a given point in time if, after initial implementation support has been withdrawn, core elements are maintained […] and adequate capacity for continuation of these elements is maintained.”	- Literature review summarizing evidence from 125 studies that “investigated whether or to what extent programs or interventions that had previously been implemented were sustained, and those that sought to understand factors that influence their sustainment.”
Chambers et al., 201310	“[P]rocess of managing and supporting the evolution of an intervention within a changing context [that involves] continued learning and problem solving, ongoing adaptation of interventions with a primary focus on fit between interventions and multi-level contexts, and expectations for ongoing improvement.”	- The Dynamic Sustainability Framework, which (1) embraces change as a central influence on sustainability, (2) postulates that adaptation is expected, and even encouraged, and (3) identifies the ecological system as an additional driver of the successful implementation and sustainability of an intervention.
Schell et al., 20138	“[T]he existence of structures and processes which allow a program to leverage resources to most effectively implement evidence-based policies and activities over time.”	- Developed based on a comprehensive literature review of studies focusing on program sustainability in public health. - Part of a framework comprising nine core domains that affect a program's capacity for sustainability (i.e., political support, funding stability, partnerships, organizational capacity, program evaluation, program adaptation, communications, public health impacts, and strategic planning). - Used to inform the development of the PSAT.73
Spencer et al., 201374	“[The] extent to which the practice can be maintained and achieve desired outcomes over time.”	- CDC conceptual framework for Planning and Improving Evidence-Based Practices.
Fleiszer et al., 201514	“We propose a broad conceptualization that consists of three characteristics: benefits, routinization or institutionalization, and development. We also suggest that sustained innovations are influenced by a variety of preconditions or factors, which are innovation-, context-, leadership- and process-related.”	- Concept analysis to increase clarity around the concept of innovation sustainability, which included seven literature reviews and 34 additional supplementary papers (theoretical and empirical articles, books, and grey literature).
SIRC Instrument Review Project, 2015; 201875,76	“[T]he extent to which a newly implemented treatment is maintained or institutionalized within a service setting's ongoing, stable operations.”	- Centralized online, open access, evolving repository of dissemination and implementation science instruments.
Hearld et al., 201623	- “We define community health collaborative sustainability as the maintenance or improvement of resources, infrastructure, activities, outcomes, and relationships to affect community health over time.” - “It also entails the processes that occur earlier in the planning and implementation phases to support such maintenance or improvement.” - “Sustainability is not a steady state that exists at any given point in time but is a multifaceted, continuous, cyclical process of organizational reflection, decision making, and change that takes into account the collaborative's original goals and population(s) of focus as well as the evolution of needs in the community and the context in which the collaborative operates.”	- Systematic review of theoretical and empirical literature on the sustainability of community health collaboratives (n = 42). - Review used as a foundation to develop a synthesized definition and conceptual groups of antecedents of sustainability. - Intended to provide guidance for practitioners, researchers, funders, and others interested in understanding what sustainability is (and is not) in a collaborative context.
Schalock et al., 201677	“Adapting successfully to change and providing a range of valued service delivery opportunities and practices in an effective and efficient manner.”	- Part of the development of a “literature-based model that incorporates the factors that drive an organization's sustainability.” - Describes how sustainability is operationalized using “a systematic approach to quality improvement.”
Moore et al., 201718	“(1) [A]fter a defined period of time, (2) the program, clinical intervention, and/or implementation strategies continue to be delivered and/or (3) individual behavior change (i.e., clinician, patient) is maintained; (4) the program and individual behavior change may evolve or adapt while (5) continuing to produce benefits for individuals/systems.”	- Developed based on a review of four knowledge syntheses13,15,19,20 on sustainability in health care interventions. - Refers to five key constructs of sustainability.
Lennox et al., 201817	Five distinct definitions of sustainability identified: (1) continued program activities; (2) continued health benefits; (3) capacity built; (4) further development (adaptation); and (5) recovering costs.	- Developed based on a systematic review of 62 publications that included a sustainability approach. - Part of a consolidated framework of 40 sustainability constructs in healthcare organized under six emergent themes: (1) the initiative design and delivery; (2) negotiating initiative processes; (3) the people involved; (4) resources; (5) the external environment; and (6) the organizational setting.
Shelton et al., 201811	“[T]he continued use of program components at sufficient intensity for the sustained achievement of desirable program goals and population outcomes.”	- Integrated Sustainability Framework.
D&I GEM, 201978	“The existence of structures and processes which allow a program to leverage resources to most effectively implement evidence-based policies and activities over time.”	- Online database providing information about behavioral, social science, and other scientific measures organized by associated constructs.
Birken et al., 202026	“[…] sustainment of implemented practices —i.e., continuous evidence-based practice use, as intended, over time in ongoing operations, often involving adaptation to dynamic contexts” while sustainability “[…] is a related, but distinct, term that refers to preparedness for sustained use or the characteristics of a new practice which will enhance its sustainment.”	- Review of nine reviews (n = 648 studies) to identify TMFs with the potential to conceptualize sustainment and to evaluate their potential contribution to develop sustainment strategies.
Moullin et al., 202038	“(1) [T]he input(s) (e.g., intervention, program, implementation strategy) continue to be delivered, through (2) routinization and institutionalization of the input(s), while adapting and evolving, and there being (3) ongoing capacity across levels (e.g., organizational, community and systems change) to support the delivery, so that (4) the outputs on the part of the health provider and/or health consumer (e.g., individual behavioral change, clinical benefits, value, impact) are maintained.”	- Focuses on sustainment as an outcome, indicating that the intervention continued over time. - Developed based on a narrative review to synthesize the literature on sustainment measures.
Palinkas et al., 202030	Four main sustainability elements identified: (1) ongoing coalitions, collaborations, networks, and partnerships; (2) infrastructure and capacity to support sustainability; (3) community need for program; and (4) ongoing evaluation of performance and outcomes.	- Qualitative study using semi-structured interviews with 45 representatives of ten grantees and nine program officers within four SAMHSA prevention grant initiatives. - Focuses on sustainability determinants and outcomes.
Shelton et al., 202031	“The continued health impact and delivery of evidence-based interventions over a longer period of time (e.g., years after initial implementation) and incorporated the complex and evolving nature of context.”	- Extension of RE-AIM “to integrate recent conceptualizations of sustainability with a focus on addressing dynamic context and promoting health equity.” - Refers to both the desired outcome and the characteristics or processes by which an intervention is more likely maintained.
Malone et al., 202179	“The degree to which an evidence-based program, policy, or intervention can deliver its intended benefits over an extended period of time.”	- Based on the definition proposed by Rabin et al.14 - Used to inform the development of the CSAT.79
Hall et al., 202221	“Sustainability is concerned with the long-term delivery and subsequent benefits of evidence-based interventions.”	- Systematic review to evaluate the quality and empirical application of measures of sustainability and sustainability determinants for use in clinical, public health, and community settings (n = 223).
Flynn et al., 202327	“Sustainability is concerned with the continued use and benefit of effective evidence-based interventions.”	- Scoping review of knowledge translation strategies for evidence-based intervention sustainability (n = 25).
Nadalin Penno et al., 202325	”… the concept of sustainability is a dynamic ongoing phase.”	- The SITS Framework, which consists of seven unique constructs, 49 determinants, and 29 related knowledge translation interventions that influence the sustainability of evidence-based practices in tertiary settings. - Developed through a systematic review and theory analysis of IS TMFs.
Zurynski et al., 202332	“Healthcare system sustainability is the ongoing capacity to deliver affordable and effective care that contributes to better health outcomes over time.”	- Systematic integrative review of barriers and facilitators associated with the sustainability of implemented and evaluated improvement programs in healthcare delivery systems (n = 124).

CDC, Centers for Disease Control and Prevention; CSAT, Clinical Sustainability Assessment Tool; CSSA, Child Survival Sustainability Assessment; D&I GEM, Dissemination and Implementation Grid-Enabled Measures database initiative; EPIS, Exploration, Preparation, Implementation, Sustainment; IS, Implementation science; NHS, National Health Service; PRISM, Practical, Robust Implementation, and Sustainability Model; PSAT, Program Sustainability Assessment Tool; RE-AIM, Reach, Effectiveness, Adoption, Implementation, and Maintenance; SAMHSA, Substance Abuse and Mental Health Services Administration; SHOUT, Sustained Health Outcomes; SIRC, Society for Implementation Research Collaboration; SITS, Sustaining Innovations in Tertiary Settings; TMFs, Theories, models, and frameworks; USAID, United States Agency for International Development.

While the concept of sustainability is still maturing, there is growing consensus that sustainability generally refers to the period following the initial implementation of an innovation—although there is considerable range in the literature regarding the time frames specified (from 6 months to several decades following initial implementation).²⁰ In contrast, Hearld et al.²³ conducted a systematic review of the sustainability of community health collaboratives and proposed a definition, which emphasizes that sustainability is not a “steady state that exists at any given point in time” but rather a “multifaceted, continuous, and cyclical process of organizational reflection, decision-making, and change.” They also found that most empirical studies providing an explicit definition of sustainability adopted a multidimensional perspective, indicating that many researchers perceived sustainability to be not “one thing” but rather a set of activities, processes, and outcomes.²³ For example, Perkins et al.⁴¹ adopted an understanding of sustainability conceptualized by Scheirer and colleagues,⁴⁵ defining sustainability as a process characterized by four major potential outcomes: maintaining program activities, continuing to serve substantial numbers of clients, building and sustaining collaborative structures, and maintaining attention to the ideas underlying the projects by disseminating them to others. Similarly, several studies of public health innovations asserted that sustainability must, at a minimum, include attention to resources, structures, and benefits for the community over time rather than focusing exclusively on any one aspect.^{23,33,41,44,60,80,81} Another common theme defining sustainability is that these resources, structures, and benefits should be consistent with both the original innovation goals and populations served while responding to changing community needs (i.e., continuous adaptation) and expanding to new populations (scalability).^{10,11,23,30,31,41,42}

A literature review (n = 125) by Wiltsey Stirman and colleagues²⁰ found that the most commonly used definition of sustainability across IS studies was the one presented by Scheirer,²² based on a sustainability definition and framework developed by Shediac-Rizkallah and Bone⁴⁷ (see Table 1). With a focus on lasting benefits, these authors^22,47 advanced the idea of “an adaptation phase that integrates and institutionalizes interventions within local organizational and cultural contexts.”¹⁰ Building on this work, Moore and colleagues¹⁸ reviewed four knowledge syntheses on sustainability in health care interventions^13,15,19,20 and highlighted important considerations regarding the concept of sustainability. They identified that some of the discrepancies across definitions used in the IS literature were related to different considerations of what was being implemented: individual behavior change or an organizational program. To address these two perspectives, Moore et al.¹⁸ proposed a comprehensive definition that included five constructs describing both individual and organizational sustainability (see Table 1). Intentionally, the authors of this latter definition did not specify a particular timeline for sustainability, as it was argued that timeline depends on the individual practice or program and the outcomes of interest. Nonetheless, use of the term “defined period of time” emphasizes that it is essential for operational definitions of sustainability used in research and implementation work to specify a timeline relevant to context. The definition proposed by Moore et al.¹⁸ helps clarify key aspects to consider regarding health care innovation sustainability and prompts researchers and implementers to think about what it is they hope to sustain at the individual, organizational, and system levels, and at the level of intervention outcomes.¹⁸ These efforts toward a comprehensive definition have been complemented by Lennox et al.,¹⁷ whose systematic review identified five distinct definitions of sustainability in health care and compiled 40 sustainability constructs into a consolidated framework organized into six themes (see Table 1).

As shown in the multiple knowledge syntheses on health care innovation sustainability, and in other recent work to conceptualize (or reconceptualize) sustainability,^13–27,32 there has been a general shift from thinking about sustainability as a “last effort” and from static conceptualizations of sustainability. Instead, researchers increasingly recognize the need for a dynamic conceptualization of sustainability, given the complex “real-world” environments in which health care innovations are implemented and sustained and that contexts may also evolve over time, requiring responsiveness, capacity-building, and adaptation.^{11,20,23,26,31} When considering the life cycle of health care innovations (i.e., a continuum from planning or pre-implementation to early, intermediate, and late implementation, then to sustainability),³¹ it may be less useful to view the sustainability of the original innovation as an “end goal”¹⁰ and, instead, consider “evolvability” throughout the dynamic life cycle of the innovation within broader communities or health systems. The aim is to achieve ongoing “fit” (i.e., a balance between sustainability of the original innovation and ongoing adaptation)⁸² and sustainable and equitable impact on health. In this conception, evolvability relates to “the adaptation of evidence-based interventions and implementation strategies in response to changing contexts and resources over time, as well as emerging needs and evidence”,³¹ which may ultimately involve de-implementation or the removal or replacement of interventions that no longer fit or are ineffective.^83,84 Moreover, Flynn and colleagues²⁷ recently highlighted that a “conceptual problem” persists in empirical studies where initial evidence-based intervention implementation and sustainability are frequently considered as two distinct or discontinued time periods (i.e., pre-implementation and implementation efforts versus sustainability). They concluded that there is a need to consider the implementation and sustainability of evidence-based interventions as a continuum in future research, and design and select IS strategies with this in mind. This perspective emphasizes planning for the sustainability of health care innovations and constant revision and adaptation of strategies to optimize sustainability and increase connectivity between research evidence and system impact.

In parallel, several investigators have argued for conceptualizations of sustainability that take into consideration the multilayered systems and factors influencing the sustainability of health care innovations.^{10,11,17,31,71} This perspective has significant implications for how people plan for sustainability and raises the question about who is responsible for sustainability planning. For example, if sustainability is conceptualized as a dynamic process that involves complex interactions between interventions, practice settings, and a broader ecological system,¹⁰ then sustainability planning should involve a dynamic, multifaceted approach engaging all who may influence—or be affected by—sustainability efforts (e.g., funders, researchers, policy makers, managers, practitioners, patients).¹⁶ There have also been ethical concerns raised regarding the sustainability of health care innovations within the broader context of translational and dissemination research.^{31,48,85–87} Indeed, many scholars have advocated greater, more thoughtful integration of a health equity perspective into research to ensure that evidence is directly useful in population-level interventions, or sufficiently sensitive to health disparities to be applicable in the social contexts of neglected or underrepresented communities.^11,85,86 To illustrate this, investigators who use an ethical lens on sustainability research may consider whether it is ethical to develop, implement, and evaluate interventions and then abandon the communities when funding ends or when the intervention does not achieve the intended benefits for research purposes.⁴⁴

These various conceptions of sustainability may underpin different paradigms or worldviews (ontological and epistemological assumptions) and, as such, yield different research questions, such as determinants or factors influencing sustainability; ways in which the health care innovation and environment adapt and evolve together in interconnected systems, ranging from micro (e.g., social interactions, work environment) to macro (e.g., societal norms, culture, economic systems) environmental systems; long-term impact of sustained clinical intervention and/or implementation strategies at the patient, practice, and/or organizational levels; and ethical and financial concerns related to health care sustainability.

Examining IS TMFs to inform sustainability research and guide how to plan for sustainability

A significant number of IS TMFs have been proposed and used to guide the planning and evaluating of health care innovation sustainability and to assist implementers to develop sustainability plans in different health care settings.^26,48–50 Generally, IS TMFs that address sustainability can be grouped into two broad categories: those that include sustainability, and those focusing on sustainability alone.

In the first category, IS TMFs tend to depict the implementation of health care innovations as a long and complex process, typically characterized by four consecutive, iterative phases that can evolve throughout the overall life cycle of the intervention implemented⁸⁸: planning/design, implementation/adoption, evaluation, and sustainability/scalability.⁴⁹ These are generally referred to as “full-spectrum knowledge translation TMFs”^49,50 or as “process” or “action” models and frameworks.⁵² TMFs in this category are commonly used to describe the process of translating research into practice or guide the planning and execution of implementation. A scoping review by Esmail et al.⁴⁹ identified 36 “full-spectrum knowledge translation TMFs” published between 1952 and 2018, with most of them being developed in the USA (n = 23/36). Well-known examples include the Consolidated Framework for Implementation Research (CFIR)⁸⁹; the Exploration, Preparation, Implementation, Sustainment (EPIS) Framework⁷²; the Knowledge-to-Action (KTA) framework⁸⁸; and the Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) framework.^65,90 A common thread among these is a culminating or final phase in the implementation process, wherein the innovation is sustained and integrated as routine practice.⁹¹ Although these TMFs have typically been applied as tools for intervention and implementation design, planning, and evaluation and, to a lesser extent, used to inform dissemination and scaling-up activities,⁵⁰ they can also be used to initiate sustainability thinking and to develop a sustainability-oriented action plan (e.g., what is being sustained and how will it be evaluated, what is the context for sustainability, who should be involved in sustainability planning). While the importance of understanding and addressing sustainability in implementation research and practice is explicitly mentioned in many of these TMFs, they do not identify or organize the specific determinants or strategies associated with sustainability success nor the factors influencing sustainability. Furthermore, concerns have been raised about the ability of these TMFs to provide concrete guidance for conceptualizing, operationalizing, measuring, and planning for longer-term sustainability in dynamic contexts and while considering health equity.^{6,11,27,31,34,38,48}

To fill this research gap, a number of scholars have focused their efforts on developing models and frameworks focused solely on sustainability, which corresponds to the second category of IS TMFs. These sustainability-focused models and frameworks can provide fertile ground for developing relevant research questions on different aspects of sustainability and provide details for planning and implementing sustainability efforts. Some of these commonly used³⁴ models and frameworks include the Dynamic Sustainability Framework,¹⁰ the Integrated Sustainability Framework,¹¹ the National Health Service (NHS) Sustainability Model and Guide,⁷¹ and the Capacity for Sustainability Framework.⁸ Most of these models and frameworks share similarities, notably that sustainability is conceptualized as a dynamic process (and sustainment as a dynamic outcome) that changes over time to meet the needs of constantly changing context, health care priorities, and evidence. Chambers et al.¹⁰ proposed the Dynamic Sustainability Framework, which focuses on “continued learning and evaluation, problem-solving, improvement and ongoing adaptation of evidence-based interventions to enhance fit with contexts and populations”.³¹ Another common feature of these models and frameworks is that they focus on factors or contextual influences that may affect the sustainability of health care innovations. For example, the NHS Sustainability Model and Guide⁷¹ revolves around three core dimensions of process, staff, and organization, which include ten factors that play a role in sustaining change in health care. The guide⁷¹ can also be used as a diagnostic and planning tool to recognize and understand the key barriers to sustainability, thereby providing guidance to implementers in identifying and improving priority areas that require strengthening to ensure an optimal position for sustainability and continual improvement. Likewise, Shelton and colleagues¹¹ proposed the Integrated Sustainability Framework¹¹ as a conceptualization of categories of key, dynamically related, multilevel factors that are important for facilitating sustainability across multiple contexts and settings. They include outer contextual factors (e.g., sociopolitical context, funding environment, community ownership), inner contextual or organizational factors (e.g., leadership, program champions, organizational support, staff stability, policy alignment), processes (e.g., partnership/engagement, training, fidelity/adaptation, strategic planning), intervention characteristics (e.g., adaptability, fit with context and population, benefits, cost), and implementer and population characteristics (e.g., individual characteristics, skills, attitude, motivations). More recently, Nadalin Penno et al.²⁵ proposed the Sustaining Innovations in Tertiary Settings (SITS) framework, which defines sustainability as an “dynamic ongoing phase” and comprises seven unique constructs, 49 determinants, and 29 related knowledge translation interventions that influence the sustainability of evidence-based practices in tertiary settings.

Using these IS models and frameworks focused on sustainability solely, researchers can formulate relevant research questions deemed priority concerns in the literature,^11,29,34 such as questions aimed at understanding factors and mechanisms of sustainability or shedding light on combinations of implementation strategies that most facilitate sustainability. To this end, the following section contains an analysis and interpretation of existing and emerging literature on the sustainability of health care innovations, summarizing priority research gaps and identifying critical avenues for future studies.

Exploring empirical research on the sustainability of health care innovations: An analysis and interpretation of the existing literature in IS

Sustainability research is rapidly evolving. One knowledge synthesis (n = 125) on the sustainability of new programs and innovations found that most of the empirical research (88; 72%) has focused on multicomponent, evidence-based interventions in a variety of health care settings and health conditions, with approximately one-third of the innovations focusing on medical interventions or health care programs, one-third on public health or health promotion programs, and one-third on mental or behavioral health interventions.²⁰ Research gaps remain in other clinical fields, including studies focused on evaluating the long-term sustainability of clinical and knowledge translation interventions for those with chronic diseases.¹⁹ An important issue to address is how and why some innovations implemented in real-world settings are sustained while others are discontinued. The need for continuing investment in effective interventions or programs is recognized as an important factor in achieving sustainability.³²

The empirical literature suggests multiple, related factors that influence sustainability.^{6,10,11,20,31,32} For example, a review examining the sustainability of evidence-based interventions and practices in public health and health care found that contextual factors such as differences in population, service structures, and sociopolitical context can influence the ways in which innovations evolve after implementation and are sustained over time.¹¹ Recently, a systematic integrative review (n = 124) of barriers and facilitators to health care program sustainability showed that strong leadership and stakeholder engagement; supportive organizational culture; intervention fit with context, need and policy; and intervention simplicity and adaptability were important factors in program sustainability.³² It also suggested that adequate resourcing, including ongoing availability of funding, staff training, and low staff turnover, as well as constrained intervention costs and alignment with organizational or broader policy or strategy, were also strongly associated with program sustainability.³² Many gaps remain in our understanding of what predicts and influences sustainability.^11,20,32,44 For example, what conditions (e.g., financial/human resources, infrastructure, leadership) must be in place to ensure long-term sustainability? Are some more critical than others? Are some combinations of conditions more successful than others and to what extent? Another area for investigation is whether factors influencing sustainability differ across populations, health care settings, and health topics or by community, cultural, economic, and sociopolitical contexts. Having a better understanding of what factors affect sustainability can inform strategies to improve the likelihood that innovations will be sustained.^30,79

The IS field has recently seen a surge of activity by investigators, health research funding agencies, and science journal editors, aiming to increase uptake of health equity considerations in study design, conduct, and reporting to ensure that research results apply to everyone. However, examination of the IS literature reveals that attention to health equity has yet to infiltrate sustainability research.^87,92 Several authors have criticized the IS field for neglecting contextual, social, and political considerations that influence health equity and sustainability.^85–87,93 Often, the nature of research evidence on which the IS field has relied on to synthesize knowledge and provide guidance comes from systematic reviews of randomized controlled trials that prioritize internal validity (e.g., is the innovation effective?) over external validity (e.g., are the results yielded generalizable to other contexts and among which populations and settings?).^11,94,95 These effectiveness studies tend to be conducted in high-income countries and with unrepresentative populations,²⁸ making the conditions for achieving and studying sustainability also unrepresentative.^11,94 In future, it will be essential for IS to recognize the critical importance of health equity in sustainability research and to continue to address issues related to health differences and social injustices. This will require paying much greater scientific attention to how to plan, monitor, and optimize sustainability in settings that serve minority, low-income, and rural populations facing health disparities.

Monitoring and measuring sustainability has also attracted considerable interest among researchers. This is because of the significant challenge of assessing sustainability for complex interventions applied to population groups with heterogeneous characteristics and diverse health conditions, contexts, and settings. For example, a review of empirical studies to investigate the sustainability of health-related programs (n = 19) revealed that about 40% to 60% continued in some form; however, the quality of evidence was relatively weak, including a lack of clear definitions for concepts, variables, and outcomes assessed, with study designs primarily consisting of self-reported assessments.²² Another scoping review on the sustainability of chronic disease health programs (n = 42) identified five definitions for sustainability outcomes, with “maintenance of program activities” being the most frequent, and evaluation periods ranging from 1 to 10  years.³⁵ It also revealed an increasing trend in the use of mixed methods designs over multiple time points to determine sustainability outcomes, although just over half of the included studies (n = 24/42) assessed the sustainability outcome only once immediately post-implementation.³⁵

Given these research gaps, several scholars have conducted research to better understand how to measure sustainability and sustainability determinants and provide guidance.^{11,20,21,30,34,35,38,45,47,73,79} For example, it has been acknowledged that sustainability outcomes have been conceptualized in many different ways, including the maintenance or improvements of health benefits or outcomes for individual patients; maintenance of community-level partnerships and continued community capacity for collaboration (i.e., the extent to which community members are educated and can access resources); maintenance of organizational practices, procedures, and policies (institutionalization); and continuation of the program activities or core elements of the original innovation.^11,35,43 Scheirer and Dearing⁴⁴ added other indicators of sustainability success, such as the diffusion and replication of the innovation in other sites and sustained attention to the issues addressed by the innovation. Additional proposed sustainability outcomes include documentation of the extent to which the innovation continues to be implemented and adaptation of the clinical and/or implementation intervention components.²⁰ Recently, Shelton and colleagues¹¹ concluded, based on the results of their extensive review of empirical research in public health and health care, that sustainability outcomes should include three core dimensions: continuation of program components, capacity-building, and continued health benefits or outcomes. A narrative review³⁸ of published sustainability measures (n = 11 measures included) highlighted that the available measures primarily assess outer context influences (e.g., community partnerships, funding arrangements, contracting, financial resources) of which many were deemed time-consuming. The review also suggested that measurement of sustainability should include measures from different perspectives, including measures relying on the inner context of evidence-based interventions (i.e., health organizations and health care professionals).³⁸

Generally, the literature suggests that a multifaceted approach to measuring sustainability is required to determine outcomes^11,35; several researchers have developed frameworks and tools to enable some standardization and guidance in sustainability assessment.^8,56,96 These include the Program Sustainability Index,⁹⁷ NHS Sustainability Index,⁷² Clinical Sustainability Assessment Tool (CSAT),⁷⁹ and Sustained Implementation Support Scale.⁹⁸ Despite these advances, researchers and implementers still face challenges related to sustainability assessment, including how to select appropriate measures and methods. It is difficult to select a measure, given the variability in the components of clinical interventions or health programs, as well as the diversity of health outcomes, contexts, and individual behaviors studied. Moreover, sustainability is a multidimensional phenomenon encompassing a diversity of forms along a continuum, with indicators of success that fall into distinct categories.^11,35,47 Because of this inherently multidimensional characteristic, assessing the multiple aspects of sustainability may require different data sources and levels of analysis¹¹ and sustainability outcome indicators may vary depending on context, needs, and populations.⁴⁶ Research funding also poses a major challenge for continued monitoring and long-term assessment; grants are usually not for multiple years, and this lack of funding calls for creativity and strategies to consider relevant and efficient research methods. Ideally, multiple sustainability outcomes should be measured, and researchers should work in partnership with stakeholders to determine and prioritize indicators and identify diverse sources of funding to assess sustainability.^11,34 Finally, as Shelton et al.¹¹ pointed out, further methodological work is needed to validate the psychometric properties of instruments and tools in different health care settings. Increasing the availability of measurement resources and culturally adapting measures to contexts and populations will contribute to more opportunities for advancing sustainability research.^11,96

A next step to advancing knowledge on factors linked to sustainability outcomes is to use this evidence, together with IS TMFs, to develop and test the efficacy of strategies to optimize sustainability.^11,26 In the IS field, there is a growing body of literature documenting the efficacy of implementation strategies (or combinations of strategies) using robust study designs, such as randomized controlled trials, which have shown positive effects on implementation quality indicators (e.g., adoption, fidelity) as well as impact on health care performance and health outcomes.^99,100 However, few studies have examined their efficacy on sustainability; there is little evidence on how to adapt strategies over time, and the impact of these adaptations on sustainability.^{9,11,27,28,40} For example, a systematic review of evidence-based intervention sustainability strategies (n = 26) found that only about one-third (35%; n = 9/26) of the included studies appropriately reported their strategies, and even fewer (n = 5/26) described the sustainability efforts and activities planned and implemented.²⁸ More recently, Flynn and colleagues²⁷ conducted a scoping review (n = 25) to consolidate evidence on which knowledge translation strategies are used and how they are used to facilitate the sustainability of evidence-based interventions in institutional health care settings and found that most studies used multicomponent strategies, with training and education as the most commonly used strategy. Many studies did not clearly report whether they used the same knowledge translation strategies for evidence-based intervention implementation and sustainability. Flynn et al.²⁷ emphasized the need to consider evidence-based intervention implementation and sustainability as a continuum in future research and to advance understanding of how to employ knowledge translation strategies for sustainability to facilitate better design, selection, and adaptation of those strategies. It will be critical for researchers to more explicitly report on their use of sustainability strategies as being central to sustainability assessment and, in doing so, better understand which intervention components are most effective.⁹ Researchers could also examine any negative or unintended consequences that could arise throughout the life cycle of the innovation and consider how to monitor and revise strategies over time.¹¹ Indeed, adaptation, and potential de-implementation, of health care innovations has been identified as an important yet understudied area with a limited evidence base to support decision-making.^27,31,83,84

In sum, sustainability research has grown rapidly in recent years. Despite this, it should be recognized that most of the efforts remain at a conceptual level, with sustainability and related concepts appearing more often in conceptual papers than in empirical articles⁴⁸; long-term evaluations of health care innovation are scarce in IS, often relegated to the “need for further research” section of publications.¹⁰¹ Although progress has been made in articulating comprehensive definitions that could be used across various research questions relevant to the study of sustainability,¹⁸ the lack of conceptual clarity and standardization of sustainability definitions and measures have hampered knowledge advances in understanding, measuring, and improving the sustainability of health care innovations. Additionally, the use of imprecise concepts and non-consistent terminology related to sustainability has challenged the field, notably by making knowledge exchange and learning and finding relevant literature difficult. Many reviews^18–20,28 have shown that most implementation studies do not contain an explicit definition of sustainability and very few prioritized the use of theoretically informed approaches to guide the planning, evaluation, and adaptation of health care innovation sustainability.

So where does the field of IS go from here? Next, we summarize priority gaps in sustainability research and highlight key areas for future research.

Identifying priority gaps in sustainability research: Concluding remarks to advance the IS field

For future research, we agree with recommendations from others^6,11 that advancing substantive research on sustainability is critical, including advancing the capacity, methods, and theoretical guidance for conducting sustainability research. There is a need to apply consistent definitions and IS TMFs across studies to strengthen evidence. We encourage researchers to carefully select a comprehensive definition and an IS TMF from the outset to strengthen consistency between underlying sustainability constructs, approaches used to study sustainability, and articulation of specific outcomes. Moving beyond defining sustainability to studying how best to optimize the sustainability of beneficial health care innovations will also advance the field. This includes prioritizing empirical work driven by health care systems and populations’ needs so that limited resources are maximized, long-term public health outcomes are achieved, community support is maintained, and ethical research standards are preserved. A related area of progress includes identifying effective strategies to improve sustainability and developing a better understanding of the mechanisms by which they operate. A final set of recommendations for IS researchers is to place greater emphasis on health equity issues in sustainability research and to develop strategies to cultivate active, engaged community partnerships and nurture shared responsibility with all health system and policy stakeholders concerned with planning and achieving sustainability. It is essential that IS researchers, funders, and policymakers commit resources and time to community engagement and partnering by co-creating infrastructures, methods, and processes to enable active involvement of multiple partners in the ongoing process of implementation and sustainability.

Building on the priority research gaps identified above from previously conducted research, we next consider how the UN 2030 Agenda for Sustainable Development¹ can be used to inform future research on the sustainability of health care innovations and highlight three emerging research directions in this area that merit further study.

THE ROAD AHEAD

Framing new research directions for the IS field for health care innovation sustainability

The broad research directions that we propose align with the UN 2030 Agenda for Sustainable Development¹ “Transforming Our World,” a plan of action to “end poverty and inequality, protect the planet, and ensure that all people enjoy health, justice, and prosperity.” We focused on the UN 2030 Sustainable Development Goal 3 “Ensure healthy lives and promote well-being for all at all ages”¹ to propose three priority areas that need to be addressed: advancing substantive research on sustainability while avoiding duplication; identifying barriers, facilitators, and strategies to sustain engagement with multiple partners; and advancing methods and tools to support monitoring, evaluation, and revision of strategies over time.

Advancing substantive research on sustainability while avoiding duplication

It is necessary to set research priorities while considering how to avoid duplication. Researchers, funders, and decision-makers have primary responsibility for reducing waste resulting from decisions about what research to do.^2,4 For this reason, we identify exploring the usefulness, validation, implications, and measurable impacts of existing IS TMFs as a priority area for research. The potential consequences of research waste on advancing sustainability research and practice should be considered—and on improving human health and well-being. We should, therefore, consider using existing IS TMFs to assess sustainability instead of creating new frameworks. A key question is whether implementation and sustainability have different predictors and underlying mechanisms and, thus, whether operationalizing and evaluating sustainability requires distinct TMFs. This work should begin by testing, refining, and/or extending existing IS TMFs and assessing the relative contributions of their constructs to predicting and optimizing sustainability. Some researchers have initiated promising research work in this direction, including adapting existing IS TMFs to make them more relevant for studying, planning, and/or optimizing sustainability.^21,26,31,40 Nathan et al.⁴⁰ noted these research gaps and recently proposed an adaptation of the Expert Recommendations for Implementing Change (ERIC) taxonomy¹⁰⁰ to incorporate a sustainability focus. Future research could explore methods for identifying and validating suitable IS TMFs for studying sustainability while ensuring they remain dynamic and focused on application in practice. Furthermore, it will be important to investigate linkages between existing IS TMFs and sustainability to develop step-by-step guidance on which TMFs to use or adapt for planning and achieving sustainability and for which contexts and circumstances. Finally, it is critical that there be more focus on understanding and proposing the right TMFs for de-implementation in the context of long-term sustainability to avoid duplication of practices or programs that are no longer recommended or lack scientific evidence.

Identifying barriers, facilitators, and strategies to sustain engagement with multiple partners

Asking “what does it take” to sustain engagement of multiple partners in implementation research and practice is critical so that what helps improve safety, health, and well-being reaches those it is intended to help. Shifting our thinking from involving community members and decision-makers in research to focusing on how research engages with communities, the health system, and politics to optimize sustainability led to three areas that urgently require further research.

First, we need to deepen our understanding of what affects partners’ capacity, motivation, and opportunity¹⁰² to engage long term. A first step would be to disentangle the multilevel factors that influence long-term engagement for different stakeholder groups, such as funders, politicians, decision-makers, leaders, evidence end users, and civil society. Researchers could examine the systemic barriers and facilitators to the sustainability of multiple-partner engagement and co-create methods/approaches that can be used to address them. For example, studies can explore how relationship-building; communication and feedback; shared responsibility; ownership of sustainability planning; policies; and financial, instrumental, and human resources contribute to building capacities that enable multiple partners to engage in supporting, monitoring, and improving sustainability practice.

Second, further work is needed to develop and test strategies that can be leveraged to strengthen the engagement of multiple partners over time to ensure the sustainability of evidence use in practice. What should be explored is how to foster commitment of policymakers and other decision-makers in planning and achieving sustainability, identifying funding strategies that generate financial resources for structures and processes that support long-term community engagement and partnership.

Third, research involving marginalized and neglected groups and people in sustainability activities and research should be a priority. Health equity considerations represent a fruitful area of investigation and should be kept in mind as a fundamental dimension that can affect the sustainability of community engagement and partnership. For example, how do cultural and traditional norms, values, and social position affect community partners in their decision-making and capacity to engage in implementation and sustainability efforts? These concerns are part of a broader area of investigation that requires more attention, namely, understanding how intersectionality^103,104; critical race theory^105,106; and concepts of power dynamics, structural racism, and social justice can be imbedded in sustainability research and practice. In parallel, there is a need to advance knowledge on best practices to meaningfully and equitably engage underrepresented groups, Indigenous communities, and citizens in sustainability research and practice. This could include conceptualizing and establishing culturally relevant support, services, and products to sustain multiple-partner engagement for different populations and contexts.

Advancing methods and tools to support monitoring, evaluation, and revision of strategies over time

Researchers need to develop and use study designs that rely on a thoughtful, strategic, closely coordinated combination of appropriate methods and measures that will capture the dynamic, non-linear nature of sustainability. For example, study timeframes should allow changes over time and long-term impacts to be examined.^11,18,20 The appropriate timeframes should be determined based on the nature of the innovation, the characteristics of targeted populations/communities, and what is relevant for the health issue being studied. However, as the sociopolitical context into which innovations are implemented is constantly changing in terms of populations, funding, health system priorities, political attention, and public interest, it is useful to assess sustainability over multiple time points.^11,20 Moreover, determining approaches/methods for studying sustainability should be based on the extent to which adaptation of intervention and/or implementation strategies is expected (or acceptable) and how this will be monitored, assessed, and revised over time.^27,44 For this reason, several scholars have recommended using prospective, multilevel, and mixed methods study designs, which are recognized as ideal for studying sustainability.^11,107 However, these types of designs generally have the disadvantage of being costly and time-consuming. Other, less onerous, rapid evaluation designs should be considered to study sustainability in future while ensuring community members collect only relevant data. Finaly, there is a need to explore the relative cost-effectiveness of different approaches or methods to identify which ones are the most cost-effective for studying sustainability and propose innovative and evolving technologies, tools and/or infrastructure that will support monitoring, evaluation, and revision of strategies over time.

CONCLUSIONS

Proctor and colleagues⁶ outlined more than 10 years ago the challenges associated with sustainability research and highlighted recommendations for accelerating and strengthening work in this area. We are seeing increased rigor and methodological advances in sustainability research, as well as a growing emphasis on planning, evaluating, and understanding strategies to optimize sustainability. Despite this, there are still many opportunities for implementation scientists and practitioners to advance research and practice in this area.

Building on priority gaps identified in prior research, we proposed three new research directions that align with the UN 2030 Agenda for Sustainable Development¹ and have the potential to advance the field. Each research direction we proposed in order to advance what is known about the sustainability of health care innovations needs time, resources, and funding, which will require strong engagement and partnership between communities, health care organizations, frontline providers, innovation developers, policymakers, implementation researchers, journal editors, and scientific conference panels. We invite all of those concerned with the sustainability of health care innovations to contribute to the advancement of research and practice in this area, which is likely to be a significant scholarly endeavor with important implications for individuals, health systems, and civil society.

AUTHOR CONTRIBUTIONS

GC conceptualized the discussion and drafted the manuscript. Both GC and SES substantially reviewed the manuscript and approved its final version.

ACKNOWLEDGMENTS

GC received scholarships as part of her postdoctoral studies from the following organizations: the Canadian Institutes of Health Research (CIHR); the St. Michael's Foundation, Unity Health Toronto; and the Centre de Recherche du Centre Intégré en Santé et en Services Sociaux de Chaudières-Appalaches (CISSS–CA). The views and opinions expressed in this manuscript do not necessarily reflect those of these funding entities. SES is funded by a Tier 1 Canada Research Chair in Knowledge Translation.