(REBALANCE) REview of Behaviour And Lifestyle interventions for severe obesity: AN evidenCE synthesis

Background: Over BMI 35kg/m2 obesity co-morbidities and their economic consequences greatly increase. Systematic review (SR) evidence on the feasibility/acceptability, and (cost) effectiveness of weight management for BMI 35kg/m2 or more is lacking. Objective: To synthesise the quantitative, qualitative, and economic evidence; develop an economic model to inform weight management programmes for people with BMI 35kg/m2 or more. Design: 5 SRs on behavioural interventions, licensed pharmacotherapy, bariatric surgery weight loss/maintenance. SR1: long-term randomised controlled trials (RCTs); SR2: long-term UK studies; SR3: qualitative, mixed-methods research on patient/provider experiences; SR4: economic evaluations of interventions; SR5: long-term RCTs lifestyle versus bariatric surgery. Economic model (micro-simulation) to estimate long-term costs, outcomes and cost-effectiveness of promising interventions, lifestyle versus surgery. Innovative methods to identify effective intervention characteristics, control for variability in support given to comparator groups. Integrate findings in realist mixed-methods synthesis. Search strategy: SRs 1-5 (no language restrictions, studies from 1990): Medline, Embase, Cinahl, CCTR, DARE, Psycinfo, NHS EED, SSCI. Contact professional, health and commercial organisations for unpublished studies; study authors for detailed descriptions of intervention and comparator group support, qualitative and process outcomes, outcome data clarification. Research strategy: SR1-2,5:outcomes are weight, cardiometabolic risk factors, disease outcomes, adverse events, quality of life. Study quality using Cochrane risk of bias and checklist used for NICE reviews. Intervention and comparator group support coded using the TIDieR, BCT (Behaviour Change Technique)-v1 taxonomy, Campbell and Cochrane Equity Methods Group checklist. Meta-analyses and (bivariate) mixed-effects meta-regression analyses to synthesise evidence and explore study, sample, intervention and comparator group characteristics associated with outcomes. SR3: feasibility and acceptability of interventions for participants and providers. Coding, thematic analysis of qualitative and mixed-methods research. Quality assessment of studies' conceptual clarity and interpretative rigor. Comparison of patterns and associations for broader interpretative themes. SR4: costs, outcomes for interventions collected. Standard checklists assess quality of the economic evaluation. Economic model: data from SRs 1,2,4,5 used to populate the UK Health Forum Obesity Micro-simulation Model , estimating cost-effectiveness of most promising interventions, including bariatric surgery, NHS perspective. Integrate findings in realist mixed-methods synthesis. Expected outputs of research: Evidence to inform guidance on weight management programmes for people with BMI 35kg/m2 or more, and future research. At least 5 research papers; conference presentations; summaries for policy makers, professionals, patients, public; online videos and podcasts. Project timetable: Months 0-2: protocol, advisory meeting. Months 2-14: SR1,SR2,SR5. Months 9-14: SR3. Months 12-17: SR4, identification of data and population of health economic model. Months 15-17: complete analyses, synthesis of SR1-5 and economic model analysis. Months 18-20: advisory meeting, final report, all other outputs. Expertise: AA,PA: SRs of obesity treatments. GM,PA,MdB: coding, meta-analysing (behavioural) interventions, including comparator group variability in RCTs. DB,LW: economic modelling and evaluations. ZS,AA: mixed-methods synthesis.