How is the behaviour change technique content of the NHS Diabetes Prevention Programme understood by participants? A qualitative study of fidelity, with a focus on receipt

Background:
The National Health Service (NHS) Diabetes Prevention Programme (DPP) is a nationally implemented behavioural intervention for adults at high risk of developing Type 2 diabetes in England, based on a programme specification that stipulates inclusion of nineteen specific behaviour change techniques (BCTs). Previous work has identified drift in fidelity from these NHS England specifications through providers’ programme manuals, training, and delivery, especially in relation to BCTs targeting self-regulatory processes.
Purpose: This qualitative study investigates intervention receipt, i.e how the self-regulatory BCT content of the NHS-DPP is understood by participants.
Methods: Twenty participants from eight NHS-DPP locations were interviewed; topics included participants’ understanding of self-monitoring of behaviour, goal setting, feedback, problem solving, and action planning. Transcripts were analysed thematically using the framework method.
Results: There was wide variation in understanding amongst participants for some BCTs, as well as between BCTs. Participants described their understanding of ‘self-monitoring of behaviours’ with ease and valued BCTs focussed on outcomes (weight loss). Some participants learned how to set appropriate behavioural goals. Participants struggled to recall ‘action planning’ or ‘problem solving’ or found these techniques challenging to understand, unless additional support was provided (e.g. through group discussion).
Conclusions: Participants’ lack of understanding of some self-regulatory BCTs is consistent with the drift across fidelity domains previously identified from NHS design specifications. Behavioural interventions should build-in necessary support for participants to help them understand some BCTs such as action planning and problem solving. Alternatively, these self-regulatory BCTs may be intrinsically difficult to use for this population.