Table 1

Domains, actions and planned methods to develop physical activity (PA) intervention for childhood cancer survivors (CCSs)

Key actions to consider for intervention development17	Domain of intervention development and associated specific action(s)16	Methods utilised, or planned, in this research to develop the BEACON intervention
Planning the process Involving stakeholders Bringing together a team	Conception
	1. Identifying the problem in need of a new intervention (including the health problem, the problematic behaviour and the target population)	Identification and evaluation of the literature on: Prevalence of cardiovascular late effects in CCSs Low PA in CCSs Benefit of PA to the health of CCSs Clinical experience/knowledge of low PA in CCSs
	Planning
	2. Setting up a planning group/development team	Establishing a multidisciplinary steering group involving: Researchers and academics with expertise in health psychology, behavioural science/intervention development, exercise physiology, PA interventions in clinical populations, digital health innovation HCPs and service providers (consultant oncologists, nurse specialists) Patient representatives
Reviewing published evidence Undertaking primary data collection Drawing on existing theories Articulate programme theory Understanding context Attending to future implementation	3. Understanding the problem to be addressed i. Understanding the views and experiences and psycho-social context of the potential target population	Use of PPI during initial stages of planning: Gaining young peoples’ views of PA and the study concept via an NHS young persons’ advisory group Consultation with CCSs on the need for PA interventions via focus group and survey methods Identification of literature reporting HCPs (who may be involved in the resulting intervention) views of PA in CCSs, and the provision of PA advice to CCSs.
	ii. Assessing the causes of the problems	Undertaking research to explore and understand CCS’s views and experiences of PA: Literature review of the barriers and facilitators to PA in CCSs Undertaking in-depth interviews with CCSs and their parents regarding their views and experiences of PA, including perceived barriers and facilitators (informed by the Theoretical Domains Framework) Creating a logic model of the problem
	iii. Describing and understanding the wider context of the target population and the context in which the intervention will be implemented	Undertaking research to explore CCS’s views of receiving PA advice in follow-up care: Survey and interviews with CCSs attending follow-up care Involving HCPs, service providers and patients in steering group and in co-production of intervention.
	iv. Identifying the effectiveness of interventions for PA in CCSs	Identification and evaluation of existing PA interventions in CCSs: Systematic reviews of PA interventions in CCSs Research evaluating PA interventions in CCSs
	v. Understanding wider stakeholders’ perspectives of problems and issues	Actively engaging with stakeholders, service providers and CCSs throughout research and in co-production of intervention.
Drawing on existing theories Articulating programme theory Understanding context Attending to future implementation	4. Making decisions about aims and goals of intervention	Based on the evidence generated in WP1, the steering group and research team will make decisions on the specific aims and goals of intervention.
	5. Identifying what needs to change and how to bring about change	Following WP1, a logical model of change will be developed for PA in CCSs drawing on the evidence and constructs from relevant theories.
	6. Specify who will change, how and when	Following WP1, the steering group and research team will break down the behavioural outcomes to consider, prioritise and map who needs to change what, how changes will occur as a result of the intervention and when these changes are expected to take place.
	7. Considering the real-world issues about cost and delivery of any intervention to reduce risk of implementation failure	Involvement of HCPs/service providers in steering group. Co-design workshops with stakeholders (including HCPs). Use of Normalisation Theory Process to inform discussion with HCPs.
	8. Considering whether it is worthwhile continuing with development of intervention	Steering group and stakeholder input on feasibility of intervention.
Designing and refining intervention	Designing
	9. Generating ideas about solutions and components and features of an intervention 10. Re-visit decisions about where to intervene	Mapping of behavioural determinants onto behaviour change techniques using Behaviour Change Wheel. Co-design workshops using creative methods and activities to enable idea generation. Input from stakeholders to make final decisions regarding the scope, the target population, key features and components of intervention which will be further refined during workshops.
	11. Make decisions about the content, format and delivery of the intervention	Findings of WP1 will be combined into a theoretical model of PA in CCSs and will inform initial ideas about content, format and delivery. Actively engaging with steering group and stakeholders via co-design workshops to obtain views on the potential content, format and delivery of intervention.
	12. Design an implementation plan, thinking about who will adopt the intervention and maintain it	Design of potential implementation plan will be informed by discussions with HCPs and other stakeholders regarding potential implementation barriers and previous research.
	Creating
	13. Make prototypes/mock-ups of the intervention where relevant	Generation and discussion of mock-ups and paper-based prototypes during co-design workshops.

CCSs, childhood cancer survivors; HCPs, healthcare professionals; NHS, National Health Service; PA, physical activity; PPI, patient and public involvement.