Title: Scalable behavioural weight management programmes for the prevention and treatment of type 2 diabetes.
Funder: Department of Health and Social Care

Abstract: Rationale Behavioural weight management programmes (BWMPs) can help prevent type 2 diabetes (T2D) and reduce risk factors for complications and the need for medication in those who have T2D. However, few are sufficiently scalable and weight is typically regained when programmes end. BWMPs that use non-specialists (health trainers, community members) and eHealth are scalable. We will evaluate whether they can achieve and maintain weight loss and reduce the incidence and complications of T2D in two populations: people at high risk of T2D, and those with a recent diagnosis. Aims To quantify the impact of scalable weight loss programmes on incidence of T2D, related complications and health resource use (Work Package 1). To develop a scalable weight loss maintenance programme that specifically targets psychological determinants of weight loss maintenance, and evaluate its impact on incidence of T2D, related complications and health resource use (Work Package 2) Methods Work Package 1 To evaluate the effectiveness and cost-effectiveness of a scalable weight loss programme for individuals at high risk of T2D, we will conduct a 5-year follow up of a randomised controlled trial (RCT). Participants (N=1269; Mean BMI 34.5kg/m2) were randomised to one of three groups (brief advice, 12 weeks Weight Watchers (WW), or 52 weeks WW) and completed measurement appointments over 2 years. At 5 years, weight, HbA1c and other risk factors will be measured by CRN nurses in local practices, and data on health resource use and quality of life will be collected. To evaluate the effectiveness and cost-effectiveness of a scalable weight loss programme for individuals recently diagnosed with T2D, we will conduct a new RCT. Participants (N=575, BMI&ge;25kg/m2, diagnosis of T2D within 3 years) will be randomised to Live Well With Diabetes (a programme that combines 52 weeks WW with diabetes education and dietician support via telephone) or to diabetes education only. Weight, HbA1c and other risk factors will be measured at 0, 6, and 12 months by CRN nurses in local practices, and data on health resource use and quality of life will be collected. In both studies we will evaluate differences between intervention groups in primary and secondary outcomes using all available data in mixed effects models under the assumption of missing at random. We will evaluate within-trial cost-effectiveness from an NHS perspective using participant level data and imputing missing data using chained equations. We will use semi-structured interviews and focus groups, and both inductive and deductive qualitative analyses, to understand the experiences of participants and practitioners, including the acceptability of the programme and perceptions of key facilitators and barriers to weight loss maintenance. To evaluate longer term cost-effectiveness of these scalable weight loss programmes and impact on incidence of T2D and related complications, we will use the NIHR SPHR Diabetes microsimulation model. We will also use a separate microsimulation model with a non-parametric approach (NHS Health Checks model) and compare findings to reduce uncertainty in estimates and increase confidence in our findings. Work Package 2 To develop a new weight loss maintenance programme, we will draw on the MRC framework for the design of complex interventions and the Intervention Mapping Protocol. The weight loss maintenance programme will be an acceptance-based behavioural programme that targets the psychological determinants of weight loss maintenance and that can be delivered in groups by trained non-specialists using a bespoke eHealth platform. We will work with patients and practitioners to iteratively develop the programme so that it meets the needs of both. We will evaluate the feasibility and acceptability of this programme in a pilot trial. Participants (N=60; previously completed a traditional BWMP &ge;3months; 50% with diabetes) will be recruited from NHS and commercial weight loss programmes and randomised to either the weight loss maintenance intervention or a control group in a 4:2 allocation. Participants will complete assessment appointments at 0 and 6 months to collect data on programme uptake and adherence and changes in weight, HbA1c and psychosocial outcomes. Findings will be used to inform the design and assess the value of a definitive trial. The SPHR Diabetes model will estimate justifiable costs for, and potential impact of, our weight loss maintenance programme. Expected Value of Sample Information methods will estimate the value of alternative trial designs in reducing uncertainty in the cost-effectiveness estimates. Projected Outputs and Patient Benefit The overall results of this research will provide policy makers and commissioners with robust evidence regarding the effectiveness and value for money of scalable BWMPs for the prevention and treatment of T2D. This will help them to choose which programmes to fund. In addition, we will have a new weight loss maintenance programme and will have determined whether it is worthwhile to pursue its further development and evaluation. If cost-effective, these programmes can be readily integrated into care pathways and significantly reduce the economic, and social burden of diabetes.

Lay abstract: Behavioural weight management programmes (BWMPs) can help prevent type 2 diabetes (T2D) and help people who have T2D reduce their need for medication and reduce their risk of complications such as heart disease. However, programmes delivered by specialist health professionals in clinical settings are too expensive to deliver to everyone who needs them. Furthermore, many people regain weight when these programmes end. We need BWMPs that help people achieve and maintain a healthy weight and can be delivered to large numbers of people. We will examine the cost-effectiveness of using non-specialists (health trainers, community members) and technology (internet, phones) to deliver BWMPs in two populations: i) people at high risk of developing T2D, and ii) those with a recent diagnosis. In our first work package, we will evaluate existing group-based weight loss programmes that use non-specialists and technology. For people at high risk of developing T2D we will follow up participants from an existing trial of a group-based programme (Weight Watchers, WW). We will: - collect 5-year outcomes for weight, blood glucose, and diabetes status - compare outcomes from 3 treatment groups (brief advice, WW for 12 weeks, WW for 52 weeks) For people with recently diagnosed T2D, we will conduct a new trial. We will: - combine WW with diabetes education and dietician support via telephone. - recruit patients diagnosed with T2D in the previous 3 years - randomly allocate participants to this new programme (WW + education) or to standard diabetes education. - compare their glucose control and body weight at 6 and 12 month follow up. In both studies, we will use interviews to understand the experiences of participants and practitioners, including the acceptability of the programme, and views about what helps (or hinders) weight loss maintenance. In our second work package, we will develop a BWMP for weight loss maintenance that uses new behavioural techniques and can be delivered in groups by trained non-specialists using technology. We will evaluate its feasibility and acceptability and estimate potential effects. For each programme, we will use modelling and statistics to estimate the longer term impacts on risk of diabetes and its complications (such as heart disease) and their value for money. We will include patients and the public in the design of the weight loss maintenance BWMP, the design and management of our studies, and the analysis, interpretation and dissemination of our findings. Our findings will provide policy-makers and commissioners with evidence regarding the value for money of scalable BWMPs for the prevention and treatment of T2D. We will also have a new weight loss maintenance programme that (if shown to be cost-effective in further evaluation) could be delivered at scale in the UK.

Research activity codes: 6.6 PSYCHOLOGICAL AND BEHAVIOURAL;3.1 PRIMARY PREVENTION INTERVENTIONS TO MODIFY BEHAVIOURS OR PROMOTE WELL-BEING
Health categories: METABOLIC AND ENDOCRINE