Secondary analysis of the Game of Stones trial for men with obesity: Examining moderator effects and exploratory outcomes

Objective
To explore whether socio-economic, health and behavioural characteristics moderate effectiveness of a text message intervention with or without financial incentives versus a control group, and to examine differences in exploratory outcomes.

Methods
Three-group randomized trial including 585 men with obesity comparing daily automated behavioural text messages for 12-months alongside financial incentives; text messages alone; or a waiting list control. Moderator analyses examined percent weight change after 12 months for 9 socio-economic and 11 health factors.
Exploratory outcomes included: self-reported physical activity, sedentary behaviour, smoking and alcohol behaviours, engagement in 15 weight management strategies, and weight-management related confidence.

Results
No moderator effects were found by any factors for either comparison versus control. There were no differences between groups for health behaviours. The texts with incentives group had higher levels of engagement in six strategies including weight goals, food changes and self-weighing, and higher levels of confidence compared to controls.

Conclusion
The Game of Stones interventions were equally effective across various sub-groups based on socio-economic, health or wellbeing status. Texts with financial incentive group participants showed better engagement for some intervention elements. The implementation of Game of Stones is unlikely to increase health inequalities. Future studies should focus on increasing engagement.