1 INTRODUCTION

Cardiovascular diseases (CVDs) are a group of disorders of the heart and blood vessels and include coronary heart disease, stroke, heart failure and other conditions. CVD has remained the leading cause of death globally for the last 20 years and is estimated to cause more than 18 million deaths each year.¹ Significant progress has been made over the past few decades in the management and treatment of CVD, particularly in the prevention of recurrent cardiovascular events in high-risk individuals such as those with previous events or known CVD (i.e., secondary CVD prevention). Secondary prevention guidelines have been developed^{2, 3} that recommend lifestyle changes for ongoing management of cardiovascular risk factors, including a healthier diet (reduction of salt, eating more fruits and vegetables), regular physical activity, medications and cessation of tobacco use and harmful intake of alcohol. However, while these behaviour changes have been shown to significantly reduce the risk of secondary CVD events,^4-6 they are also shown to be difficult to sustain long term.^7-9

Several effective approaches to support CVD patients in adopting these preventive behaviours have been established, including engagement in lifestyle modification programmes, use of technology-based interventions (e.g., telehealth, mobile health applications) and cardiac rehabilitation.⁵ However, despite good evidence for their effectiveness, these programmes are not always well-utilized or accepted by the target population. For example, the benefits of cardiac rehabilitation are well-recognized and include lower mortality rate, reduced risk of hospital admissions and improved health-related quality of life.^{10, 11} However, cardiac rehabilitation continues to have poor attendance rates, with only 15%–30% of eligible patients engaging with the programme.^{12, 13} To address poor uptake, policymakers and healthcare providers need to ensure that interventions are well-accepted and adapted to the specific needs and perceptions of the target population.^{14, 15} One way to achieve this is for researchers to work with end-users and nonacademic stakeholders in the development of interventions; this is known as co-design.

The engagement of stakeholders in the development of interventions or public health initiatives is captured in the literature under different terminologies such as ‘co-design’, ‘co-production’, ‘co-creation’, ‘participatory action research’ or ‘user-centred design’.¹⁶ These terms are often used interchangeably by authors and are understood to describe equivalent approaches to stakeholder engagement. Co-design is a process in which targeted end-users and other relevant stakeholders form a partnership with researchers and work together on all aspects of intervention development, from understanding the needs of end-users to content development and pilot testing.¹⁷ There are a number of co-design research frameworks in the literature, all describing a similar series of sequential phases and core principles, which include equity (shared decision-making across all stages), understanding experiences (co-learning with a mutual exchange of information between partners) and improving services or health outcomes (development of a programme based on the findings).¹⁷ Co-design is a relatively new concept within healthcare, although over the past decade, researchers and healthcare providers have increasingly involved consumers and nonacademic stakeholders in the development of public health interventions to improve process and health outcomes.¹⁸ Involving consumers in this way has been shown to increase acceptance, uptake, long-term adherence and satisfaction with interventions, as well as improve the health outcomes of end-users.^{19, 20} For this reason, evidence for the use of the co-design approach in the development of healthcare interventions is increasing across many disciplines.²¹ However, despite an abundance of CVD intervention studies in the literature, few describe the use of co-design methodologies. Utilizing the co-design approach could address potential barriers to the uptake of an intervention and may deliver more effective and sustainable solutions to CVD secondary prevention.^{22, 23}

By summarizing the key processes used to develop these CVD interventions, we intend to improve the knowledge base for co-design in CVD research and provide a guide for researchers considering using these methods.

2 METHODS

A scoping review was undertaken to address our research questions following a methodological framework to guide the review process.²⁴ The review is reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) Checklist²⁵ and is registered with PROSPERO (CRD42021291841).

3 RESULTS

3.1 Study selection

Following the removal of duplicates, 5892 articles were retrieved from the electronic search. Of these, 5738 articles were excluded based on the review of the title and abstract, and the full text was obtained for the remaining 154 articles. Based on the authors' assessment, 22 unique studies^28-49 published across 45 articles met the eligibility criteria and were included in this review (Figure 1).

4 DISCUSSION

This is the first review on the use of co-design methodology in the development of CVD secondary prevention interventions. Our findings confirmed that the co-design approach is still an emerging field in CVD research, as evidenced by the small number of studies found in the literature with the majority of these published in the past 5 years. Studies were implemented across various settings with consumers and stakeholder groups most frequently consisting of patients and healthcare professionals, respectively. Consistent with co-design literature,⁵⁰ varying models of co-design methodology utilizing different research activities were reported by studies. Findings from this review suggest it is feasible to apply the principles of co-design in various settings and CVD population groups.

The lack of a singular consistent definition of ‘co-design’ made it difficult to retrieve relevant literature for this review. Many research co-design approaches were identified within the literature, with extensive variability in the methods, research phases, participants and levels of involvement. Based on the sufficiency of reporting checklist, most studies in this review described their co-design methodology clearly and adequately, making it easier for others to replicate co-design in their own research. Conversely, previous reviews of co-design have reported that studies provided insufficient details of their co-design activities in their methods to establish what was actually involved.^{18, 50, 51} This difference in reporting may be explained by our comprehensive inclusion criteria to draw together the varying definitions and terminology used, which was guided by a co-design framework.¹⁷ During the full-text review stage of the literature search, study methodology was evaluated against Boyd et al.'s¹⁷ co-design framework to determine if the intervention was developed using established co-design methodology; that is, consumers and/or relevant stakeholders were involved in most aspects of intervention development, from the needs assessment through to content development and pilot testing. Over 40 studies were excluded based on this definition, including 6 studies that specifically stated they used a co-design or participatory action research approach. After closer inspection of these six studies, consumers and stakeholders either participated only in a need assessment to guide researchers in the development of the intervention (Exploratory Phase) or were asked to provide feedback on an intervention that was already developed by the researchers (Development Phase). For the purposes of this review, this was not considered a ‘true’ co-design approach. The heterogeneity in approaches, variable use of terminology and gaps in reporting indicate that this area of research may benefit from a framework that sets out the core principles for cardiac services seeking to use co-design.

Engagement with consumers and stakeholders is critical to true and successful co-design.¹⁷ Although all 22 studies reported learning about consumers' or stakeholders' experiences with CVD (i.e., performed a needs assessment) and included them in the development phase of the intervention, few studies reported methods of establishing meaningful relationships with consumers and stakeholders. This involved strategies such as developing a community advisory board comprised of key stakeholders, identifying local champions to oversee the study, and engaging with key staff before beginning the research to help guide the co-design process. Previous studies have identified that selecting stakeholders strategically to fit project needs, adapting the project to the practical needs of stakeholders and clearly defining roles and expectations for stakeholders, as well as responsibilities and powers, are key strategies to establishing meaningful partnerships in research.⁵² Broad engagement principles such as these need to be present when using co-design methods to develop effective and participatory research relationships, rather than engaging stakeholders merely to fulfill a requirement. Additionally, having stakeholders involved early means that their experiences and requirements can be taken into account at the start of the process rather than researchers presuming to know what is required.⁵³ Researchers and policymakers who are new to the co-design approach should consider how involving end-users and stakeholders in the study planning phase can assist in prioritizing research topics, setting research agendas and helping to refine research design and processes.

Assessing the effectiveness of co-designed interventions in formal evaluations and clinical trials is important to determine the efficacy of this method.¹⁸ There is minimal literature that has evaluated the direct links between co-designed CVD interventions and improved patient experiences or outcomes. In this review, intervention effectiveness was only assessed in 10 studies and mixed results were reported across studies. While few studies to date have investigated the effectiveness of co-designed interventions in CVD secondary prevention, a recent systematic review and meta-analysis found that co-designed public health interventions for various health conditions can improve short-term health outcomes such as self-efficacy, healthy behaviours and lifestyle changes, health service access and physical health.⁵⁴ Further to this, the majority of studies included in this review can be considered complex interventions (i.e., having multiple interacting components or target groups and settings).⁵⁵ An important element of complex interventions is understanding ‘how’ and under what circumstances an intervention can achieve its desired effect, often termed the ‘mechanism of change’. These mechanisms, or causal links, are more transparent when ‘theory’ is applied to the development of an intervention, also facilitating meaningful evaluation of outcomes.⁵⁵ Of the included studies, only seven applied a theoretical framework during the intervention development. These included the Behaviour Change Wheel,^{30, 46} the Social Cognitive Theory,⁴⁴ the Medical Research Council (MRC) framework,³⁸ the Ophelia approach²⁸ and the Integrated Knowledge Translation theoretical approach.^{46, 49} However, the way in which these theories informed evaluation was not clearly articulated. In other studies, authors proposed suggestions for mechanisms of change, such as tailoring interventions to the needs of end-users,^{35, 40-42} but these were not underpinned by a theoretical framework. To advance robust reporting of co-designed interventions, authors are encouraged to consider the mechanisms of action in both the design and evaluation of their interventions and to explicitly describe these to readers using public health frameworks such as the Template for Intervention Description and Replication (TIDieR) checklist.⁵⁶

The issue of implementation is increasingly understood to be an integral point of attention throughout the course of intervention development, from conceptualization to evaluation. During the pilot testing/evaluation phase, aspects of implementation are typically addressed through process evaluations,⁵⁷ and more recently, through innovative hybrid effectiveness-implementation study designs that provide outcomes on both intervention effectiveness and implementation (e.g., implementation fidelity, the proportion of reach and barriers to implementation).⁵⁸ In contrast, issues of implementation are generally addressed within the stages of the co-design approach through dedicated stakeholder engagement. The MRC framework for complex interventions highlights the value of stakeholder engagement throughout all stages of intervention development and evaluation: prioritizing research questions, development of the programme theory, intervention refinement and practical support for evaluation.⁵⁵ Engagement of stakeholders can also help to clarify which contextual factors might influence both the implementation and effectiveness of an intervention.⁵⁹ Understanding the role of these contextual factors is particularly important when considering scalability (i.e., implementing a locally designed intervention in multiple settings where operating systems and delivery of care are likely to vary).⁵⁵ Involving stakeholders who hold relevant, lived experience and including a dedicated focus on implementation in the co-design process may support successful upscaling and dissemination of interventions to a wide range of settings.

Although co-design has been used frequently to develop health interventions for ‘underserved’ population groups such as people with disabilities or from culturally and linguistically diverse communities,^{60, 62} it was interesting to find that only one study involving these populations was identified in this review. Pekmezaris et al.³⁷ included Black and Hispanic patients and disparity experts in their study to create a telemonitoring intervention for heart failure that is acceptable and feasible for use with a lower-income, Black and Hispanic patient population. More studies in this review may have included participants representing diverse groups; however, our sufficiency of reporting analysis found that studies often lacked an adequate description of participant characteristics. The burden of CVD is higher among minority groups and people living with socioeconomic disadvantage, which and is associated with increased mortality rates and a greater risk of subsequent cardiac events.⁶³ Evidence also shows that these populations receive suboptimal healthcare access compared to other population groups.⁶⁴ Healthcare services have an important role to play in addressing this social gradient,⁶⁵ by ensuring that the care they provide is accessible for all, including culturally and linguistically diverse communities, minority groups and those with lower socioeconomic status.⁶⁶ Use of the co-design approach can take context-specific challenges of ‘underserved’ population groups into consideration to provide a culturally appropriate and logistically sound CVD intervention that is feasible and acceptable.

5 CONCLUSION

We conducted a scoping review to examine how studies have undertaken co-design to develop CVD secondary prevention interventions. In doing so, we make several practical contributions to the literature. First, the findings from this review provide methodological considerations that can guide researchers and healthcare services in understanding how the co-design approach may be implemented to develop locally feasible, acceptable and sustainable strategies to improve outcomes for CVD populations. Second, by adapting Boyd et al.'s¹⁷ co-design framework, we mapped the co-design activities used in studies to the six steps of co-design to ensure sufficient reporting of methods for future research. Finally, we identified the knowledge gaps in CVD co-design research (e.g., limited research in post-design evaluation, inadequate reporting of levels of consumer involvement), highlighting the importance of assessing the effectiveness of co-designed interventions in future research.

AUTHOR CONTRIBUTIONS

The study was conceived by Jason Talevski and Alison Beauchamp. Jason Talevski conducted the literature search and all authors contributed to the study selection. Jason Talevski and Alison Beauchamp extracted, analysed and interpreted the data. Jason Talevski, Roman Falls, Natali Cvetanovska and Alison Beauchamp conducted the critical appraisal of studies. Jason Talevski drafted the manuscript, and all authors critically revised the manuscript and approved the final version.

CONFLICT OF INTEREST

The authors declare no conflict of interest.