Are behavioural text messages with and without endowment incentives effective and cost-effective for men with obesity? The Game of Stones randomised controlled trial.

Conference:

SAPC ASM 2024 - Bristol

Talk Code:

8A.3

Presenter:

Pat Hoddinott

Co-authors:

Catriona O’Dolan, Lisa Macaulay, Stephan Dombrowski, James Swingler, Seonaidh Cotton, Abraham Getanah, Kate Hunt, Michelle McKinley, Katrina Turner, Kate Hunt, Marjon Van der Pol, Graeme Maclennan, on behalf of the Game of Stones research team

Author institutions:

University of Stirling, University of Aberdeen, Queens University Belfast, University of Bristol

Problem

Men with obesity are an underserved population as they engage less frequently with weight management interventions than women. Effective, scalable, low-cost interventions with wide reach are needed. Aims: to estimate the difference in percentage weight change after 12 months for men with obesity who receive texts with financial incentives, texts only or waiting list for texts and to ascertain cost-effectiveness.

Approach

In this three-group assessor blind randomised controlled trial men with body mass index > 30 kg/m2 were invited through general practice, community information and social media targeting disadvantaged areas in Belfast, Bristol and Glasgow. Participants received daily automated behavioural texts for 12 months: the texts alongside incentives where money was deducted for not meeting verified weight loss targets (5% at 3 months; 10% at 6 months; 10% at 12 months) from an initial endowment of £400; or a 12-month waiting list for texts. Intervention groups received localised web-based information, signposting to services and self-monitoring pages. All groups received baseline weight management information and a pedometer. The primary outcome was % weight change from baseline at 12 months (minimum clinically important difference: 3%).A cost-effectiveness analysis from a health service perspective over 12 months and lifetime horizon, compared incremental cost per QALY for each intervention group with the waiting list control. An existing PRIMEtime Cost-Effectiveness obesity model was used to capture relevant costs and benefits beyond the trial period.

Findings

Participants’ mean (Standard Deviation, SD) age was 50.7 (13.3) years; 227 (39%) lived in disadvantaged areas; 426 (73%) provided weight at 12 months. Mean percentage weight change from baseline (SD) was -4.8% (6.1) for texts with incentives, -2.7% (6.3) for texts only, and -1.3% (5.5) for waiting list. Texts with incentives were superior to waiting list, mean difference -3.2% (97.5 % Confidence Interval (CI), -4.6, -1.9, p <0.001); texts only were not -1.4% (97.5 % CI -2.9, 0.0, p =0.053). Mean weight changes were -5.7kg (SD 7.4), -3.0kg (SD 7.5), and -1.5kg (SD 6.6). For texts with incentives the number needed to treat (97.5% CI) for ≥5% and ≥10% weight loss at 12 months is 4 (3,7) and 5 (4,9). Local service engagement and weight-loss drug use were low and did not differ across groups.The average incentive paid was £128/participant. Texts with incentives and texts only are cost-effective compared to the waiting list when modelled over a lifetime. The optimal strategy varies depending on assumptions around weight regain after 12 months.

Consequences

Texts with incentives are effective and cost effective for weight loss and can potentially be delivered at scale. Texts only are not effective but were cost effective. With wide reach and only four in person weight assessments over 12 months, both interventions offer an alternative to intensive programmes.

Submitted by:

Pat Hoddinott

Funding acknowledgement:

This trial is was funded by the National Institute for Health and Care Research (NIHR), UK (Ref: NIHR 129703). using UK aid from the UK Government to support global health research. The views expressed in this publication are those of the authors and not necessarily those of the NIHR or the UK government. This project was supported by NHS Bristol, North Somerset and South Gloucestershire Integrated Care Board; NHS Greater Glasgow and Clyde and The Public Health Agency, Northern Ireland.