Long-term Effects of Text Messages with Financial Incentives for Men with Obesity: Two-year Follow-up of the Game of Stones trial

Objectives

To compare the difference in percentage weight change at 24 months following a 12-month text messaging with financial incentive intervention compared to a waiting list control group, and to compare the text messaging alone group to the control group.

Design

Assessor-blinded three-arm randomised clinical trial.

Setting

Three disadvantaged communities from the UK.

Participants

585 men with body mass index (BMI) of ≥30kg/m ² enrolled between July 2021 and May 2022, of which 377 participants (64%) completed 24 months’ follow-up.

Interventions

12 months of daily behavioural text messages combined with financial incentives; 12 months of the same text messages alone; or waiting for 12 months followed by receipt of the first 3 months (months 12-15) of text messages (control).

Main outcome measures

Within-participant change from baseline weight.

Results

At 24 months, the mean percent weight change (standard deviation) was −3.9% (6.9%) for the text messaging with financial incentives group, −2.6% (6.8%) for the text messaging alone group, and −2.2% (6.8%) for the control group. Compared with the control group, the mean percent weight change was not significantly greater in the text messaging with financial incentives group (mean difference, −1.0%; 97.5% CI, −2.6 to 0.6; P = .22) or the text messaging alone group (mean difference, −0.0%; 97.5% CI, −1.6 to 1.5; P = .95). At least 5% weight loss at 24 months was achieved by 52 (40%) participants in the text messaging with financial incentives group; 32 (28%) in the text messaging alone group and 43 (32%) in the control group.

Conclusions

A scalable, low-cost text message with financial incentives intervention supported clinically relevant maintenance of weight loss 12 months after the intervention ceased, including those from disadvantaged backgrounds.

What is already known on this topic

• Men, particularly those in lower socio-economic groups, engage less frequently in existing weight loss interventions and services, and might benefit from gender-sensitized interventions.

• The Game of Stones trial showed that a 12-month intervention consisting of text messaging with endowment financial incentives resulted in statistically significant weight loss in men with obesity compared with control.

What this study adds

• At 24 months, participants receiving 12 months of behavioural text messages with financial incentives displayed continued weight loss which is likely to be clinically important for some men.

• This digital, scalable, low risk text messaging with financial incentives intervention, with low participant and staff burden, shows promise for longer-term weight maintenance in men, including those living in the most deprived areas.