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

Lisa Macaulay*, Catriona O’Dolan, Alison Avenell, Paula Carroll, Seonaidh Cotton, Stephan Dombrowski, Andrew Elders, Beatriz Goulao, Cindy Gray, Fiona M. Harris, Kate Hunt, Frank Kee, Graeme MacLennan, Matthew David McDonald, Michelle McKinley, Rebecca Skinner, Claire Torrens, Martin Tod, Katrina Turner, Marjon van der PolPat Hoddinott

*Corresponding author for this work

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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.

Original languageEnglish
Article number582
Number of pages19
JournalTrials
Volume23
Issue number1
Early online date22 Jul 2022
DOIs
Publication statusE-pub ahead of print - 22 Jul 2022

Keywords

  • cost-effectiveness
  • financial incentives
  • health inequalities
  • men with obesity
  • process evaluation
  • randomised controlled trial
  • text messages
  • weight management

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