Effectiveness and cost-effectiveness of text messages with or without endowment incentives for weight management in men with obesity (Game of Stones): study protocol for a randomised controlled trial

Abstract

Background Obesity increases the risk of type 2 diabetes, heart disease, stroke, mobility problems and some cancers, and its prevalence is rising. Men engage less than women in existing weight loss interventions. Game of Stones builds on a successful feasibility study and aims to find out if automated text messages with or without endowment incentives are effective and cost-effective for weight loss at 12 months compared to a waiting list comparator arm in men with obesity. Methods A 3-arm, parallel group, assessor-blind superiority randomised controlled trial with process evaluation will recruit 585 adult men with body mass index of 30 kg/m2 or more living in and around three UK centres (Belfast, Bristol, Glasgow), purposively targeting disadvantaged areas. Intervention groups: (i) automated, theory-informed text messages daily for 12 months plus endowment incentives linked to verified weight loss targets at 3, 6 and 12 months; (ii) the same text messages and weight loss assessment protocol; (iii) comparator group: 12 month waiting list, then text messages for 3 months. The primary outcome is percentage weight change at 12 months from baseline. Secondary outcomes at 12 months are as follows: quality of life, wellbeing, mental health, weight stigma, behaviours, satisfaction and confidence. Follow-up includes weight at 24 months. A health economic evaluation will measure cost-effectiveness over the trial and over modelled lifetime: including health service resource-use and quality-adjusted life years. The cost-utility analysis will report incremental cost per quality-adjusted life years gained. Participant and service provider perspectives will be explored via telephone interviews, and exploratory mixed methods process evaluation analyses will focus on mental health, multiple long-term conditions, health inequalities and implementation strategies. Discussion The trial will report whether text messages (with and without cash incentives) can help men to lose weight over 1 year and maintain this for another year compared to a comparator group; the costs and benefits to the health service; and men’s experiences of the interventions. Process analyses with public involvement and service commissioner input will ensure that this open-source digital self-care intervention could be sustainable and scalable by a range of NHS or public services. Trial registration ISRCTN 91974895. Registered on 14/04/2021.

Designing financial incentives for health behaviour change: a mixed-methods case study of weight loss in men with obesity

“…A stakeholder workshop was used to decide on the final design. The final incentive design was tested in a feasibility trial (Dombrowski et al 2020) which showed promise, and a full definitive trial is in progress (Macaulay et al 2022). Three minor modifications were required, which endorse our approach to incentive design as fit for the purpose of effectiveness Firstly, all mention of charity donations was removed from information materials; secondly, the incentive provider named on the mock cheque was changed from University of Stirling to Game of Stones Research, as the intervention will be tested across the UK and men in other parts of the UK are likely to be unfamiliar with the University of Stirling; and, thirdly, an online audio-visual explanation of the incentive scheme was developed, in addition to the written participant information leaflet (see supplementary material).…”

Text Messages With Financial Incentives for Men With Obesity

“…Final follow-up occurred June 2023. The trial protocol can be found in Supplement 1 13 and the statistical analysis plan in Supplement 2. Eligible men were randomized to 1 of 3 groups: text messaging with financial incentives for 12 months; text messaging alone for 12 months, or waiting list (control) for 12 months.…”