Effectiveness and cost-effectiveness of text message and financial incentives for weight management in men with obesity: The Game of Stones RCT
Bibliographic record
Abstract
Background Men with obesity infrequently engage with weight management services. Objectives To determine: (1) percentage weight loss at 12 and 24 months for text messages with or without financial incentives compared to control; (2) secondary outcomes; (3) cost-effectiveness; (4) moderators of effectiveness and (5) participant and stakeholder perspectives. Design and methods Assessor-blinded randomised controlled trial. United Kingdom National Health Service perspective cost-effectiveness over 24 months and modelled lifetime horizon. Mixed-methods process evaluation. Setting and participants Five hundred and eighty-five men with body mass index ≥ 30 kg/m 2 enrolled (July 2021–May 2022) in Belfast, Bristol and Glasgow; final follow-up June 2024. Interventions Random allocation to 12 months of behavioural text messages plus financial incentives ( N = 196), same texts alone ( N = 194) or 12-month waiting list control group offered 3 months of texts between 12 and 15 months ( N = 195). A £400 financial incentive was lost if weight loss targets were not met. Main outcome measures Weight change as a percentage of baseline weight at 12 and 24 months comparing control with (1) texts with financial incentives and (2) texts alone. Results Of 585 men (mean age 51 years; mean weight: 119 kg), 227 (39%) lived in lower socioeconomic areas, 146 (25%) reported a mental health condition and 253 (40%) had multiple long-term conditions. Follow-up was completed by 426 (73%) at 12 months and 377 (64%) at 24 months. At 12 months, mean percentage weight changes (standard deviation) were −4.8% (6.1) (−5.7 kg), −2.7% (6.3) (−3.0 kg), and − 1.3% (5.5) (−1.5 kg) for the incentives, text-only, and control groups, respectively. Compared to control, weight loss was significantly greater with incentives [−3.2% (97.5% confidence interval −4.6 to −1.9; p < 0.001)] but not texts alone (−1.4%; confidence interval −2.9 to 0.0; p = 0.053). At 24 months, changes were −3.9% (−4.6 kg), −2.6% (−3.1 kg), and −2.2% (−2.6 kg), no significant between-group differences. Intervention costs were £243 for texts with incentives, £110 for texts alone. There were no significant differences between 24-month costs and quality-adjusted life-years. Long-term modelling found texts with incentives versus control were: quality-adjusted life-year difference (95% confidence interval): 0.02 (0.007 to 0.029); cost difference: £176 (£43; £311); incremental cost-effectiveness ratio: £9748 (£7705 to £11,791). For texts alone versus control: quality-adjusted life-year difference: 0.03 (0.015 to 0.037); cost difference: £16.5 (−£117; £152); incremental cost-effectiveness ratio: £628 (−£5914 to £5384). There were no moderator effects for socioeconomic, health or well-being status for either comparison versus control. The texts with incentives group had a higher engagement in weight goal setting, food changes, self-weighing, confidence, satisfaction and quality of life compared to the control. Limitations Generalisability to women, diverse ethnic groups and people with low literacy is uncertain. Not generalisable to people with no mobile phone access. Retention was lowest in the text messages alone group. Conclusions Texts with financial incentives have a modest but important effect to 12 months with clinically relevant weight loss maintenance to 24 months, are cost-effective and equally effective regardless of socioeconomic or health characteristics. Future work Implementation, adapt for women, other cultures and longer-term follow-up. Funding This synopsis presents independent research funded by the National Institute for Health and Care Research (NIHR) Public Health Research programme as award number NIHR129703.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.025 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".