A cluster randomised controlled trial of the Wellbeing in Secondary Education (WISE) Project - an intervention to improve the mental health support and training available to secondary school teachers: protocol for an integrated process evaluation

Background: Secondary school teachers have low levels of wellbeing and high levels of depression compared with the general population. Teachers are in a key position to support students, but poor mental health may be a barrier to doing so effectively. The Wellbeing in Secondary Education (WISE) project is a cluster randomised controlled trial (RCT) of an intervention to improve the mental health support and training available to secondary school teachers through delivery of the training package Mental Health First Aid and a staff peer support service. We will conduct a process evaluation as part of the WISE trial to support the interpretation of trial outcomes and refine intervention theory. The domains assessed will be: the extent to which the hypothesised mechanisms of change are activated; system level influences on these mechanisms; programme differentiation and usual practice; intervention implementation, including any adaptations; intervention acceptability; and intervention sustainability. Methods: Research questions will be addressed via quantitative and qualitative methods. All study schools (n = 25) will provide process evaluation data, with more detailed focus group, interview and observation data being collected from a subsample of case study schools (4 intervention and 4 control). Mechanisms of change, as outlined in a logic model, will be measured via teacher and student surveys and focus groups. School context will be explored via audits of school practice that relate to mental health and wellbeing, combined with stakeholder interviews and focus groups. Implementation of the training and peer support service will be assessed via training observations, training participant evaluation forms, focus groups with participants, interviews with trainers and peer support service users, and peer supporter logs recording help provided. Acceptability and sustainability will be examined via interviews with funders, head teachers, trainers and peer support services users, and focus groups with training participants. Discussion: The process evaluation embedded within the WISE cluster RCT will illuminate how and why the intervention was effective, ineffective or conferred iatrogenic effects. It will contribute to the refinement of the theory underpinning the intervention, and will help to inform any future implementation.