Effectiveness and cost effectiveness of text message and endowment incentives for weight management in men with obesity: the Game of Stones randomised controlled trial

RESEARCH QUESTION Are automated ‘Short Message System’ (SMS) texts, delivered to support behaviour change, with or without endowment Incentives (I), effective and cost-effective for weight-loss at 12 months (M) compared to a waiting list control in men with obesity? BACKGROUND Obesity increases the risk of type 2 diabetes, heart disease, stroke, mobility problems and some cancers, and its prevalence in rising. Men engage less than women in existing weight loss interventions. This trial builds on our Game of Stones NIHR PHR-funded feasibility study. AIMS 1.Conduct a 3-arm RCT to estimate between group weight-loss difference at 12M for men with obesity who receive i) SMS+I; ii) SMS only; iii) 12M wait list for SMS 2.Assess differences between groups in secondary outcomes 3.Assess the cost-effectiveness of SMS+I and SMS only compared to a wait list control 4.Understand men’s experiences of the intervention with a focus on living with mental health conditions and multiple long term conditions; and service providers perspectives’ 5.Follow up men at 24M (12M after intervention ceases) and request consent for linkage to long-term health outcome data 6.Refine the digital programming for future scalability and implementation. METHODS Three-arm, assessor-blind, randomised controlled trial (1:1:1) recruiting 585 men with obesity via community venues (50%) or GP invitation letter (50%), purposively targeting disadvantaged areas; qualitative sub-study; cost-effectiveness modelling POPULATION: Adult men with Body Mass Index of 30kg/m2 or more SETTING: 3 centres (Glasgow, Belfast, Bristol) including GP practices and diverse venues INTERVENTIONS 1) SMS ONLY: daily texts for 12M with evidence and theory-based behaviour change techniques embedded; 2) SMS + I: as above + financial incentives based on loss aversion theory. The full incentive endowed at the start is paid at 12M if all verified weight loss targets from baseline are met: 5% of weight lost at 3M, 10% lost at 6M and 10% lost at 12M. Some money is lost for each target that is not met. CONTROL: 12M wait list then SMS for 3M PRIMARY OUTCOME: mean between-group % differences in weight-loss at 12M from baseline POWERED TO DETECT 3% weight loss at 12M SECONDARY OUTCOMES: physical activity; alcohol consumption; smoking status; satisfaction; Warwick-Edinburgh Mental Well-Being Scale; PH-4; EQ5D-5L-AD; 24M weight loss; adverse events; EQ5D-5L. PROCESS OUTCOMES: incentives gained/targets met; SMS delivered; GP/Community recruitment strategy, socio-economic status, co-morbidity; behaviour strategies QUALITATIVE RESEARCH: telephone interviews with: i) 30 participants about their experiences at 12M and 24M; ii) 12-16 service commissioners about scalability, iii) 8 -12 participants about experiences of living with obesity and mental health conditions at 12M iv) 8-12 participants about experiences of living with obesity and multiple long-term conditions HEALTH ECONOMIC EVALUATION: Costs a) over the trial and b) over modelled lifetime: including health service resource-use and QALYs. A cost-utility analysis will report incremental cost per QALY gained. TIMELINE M0-6 set-up; M7-15 recruitment (24 men/month/centre); M7-M27 3, 6 and 12M data collection; M28-33 data analysis; M19-36 qualitative study; M31-39 follow-up at 24M; M28-40 economic analysis; M40-42 final report and dissemination. ANTICIPATED IMPACT AND DISSEMINATION We will work with PPI and service commissioners so that this open-source digital self-care intervention could be centrally or locally sustainable and scalable by a range of NHS or public services. Dissemination will be with Men’s Health Forum to men, the public, policy makers, NHS commissioners and staff via media, online fora, stakeholder events and publications.