The study has been designed as a feasibility study with an integrated process evaluation following MRC guidance (Craig et al., 2008; Moore et al., 2015). The process evaluation data collection has been modelled on the COM_B and the Behaviour Change Wheel framework (BCW) frameworks (Michie et al., 2014; Barker et al., 2016) addressing: policy context; intervention functions; target behaviours; and outcomes. As part of the process evaluation the investigators will also use Consolidated Framework for Implementation Research (CFIR) to study how the programme can be optimally embedded within routine diabetes care, and to optimise the design of a subsequent trial (Murray et al., 2010). The investigators will conduct a feasibility randomised controlled trial (waiting-list design) with integrated process evaluation designed following the Medical Research Council's (MRC) Complex Intervention Evaluation Framework (Craig et al., 2008). Sixty young people will be randomised to either YES intervention or waiting-list control and evaluate outcomes at 6-months; at this point the waiting list participants will be offered the YES intervention with further follow-up at 12 months.
The proportion of patients achieving the progression criteria and the target reduction in glycated haemoglobin (HbA1c) from baseline to follow-up (6 and 12 months) will be estimated in both intervention and waiting list control groups. The investigators will also estimate the standard deviation (SD) of the mean difference between the intervention and waiting list control groups in HbA1c at 6 and 12 months. These statistics will help to inform the sample size calculation of a larger trial.
The process evaluation will consider the setting, implementation, and mechanisms of action of the programme to support interpretation of the outcomes. The process evaluation uses a standardised taxonomy for understanding implementation (Julious, 2005; Proctor et al., 2011), and will assess: the reach, fidelity and receipt of the programme; acceptability, appropriateness and feasibility; unintended consequences; potential sustainability; and implementation costs and strategies. In addition, potential mechanisms of action will be elicited, including changes in behaviours, and how they relate to programme delivery and outcomes.
The investigators will use a mixed-method approach with validated implementation outcome surveys (Powell et al., 2015) and one-to-one interviews with young people, their relatives and healthcare professionals. The data collection tools and analytic models have been designed with reference to the BCW (Michie et al., 2014) and to provide the data for CFIR analysis, considering the barriers and facilitators to the intervention. To ensure relevance and feasibility, the data collection procedures will be refined with the study patient and public involvement groups. Data collection will be conducted at multiple time points to provide opportunities for data triangulation and subsequent theory generation.
