Behavioural weight management programmes can help people lose weight and reduce their risk of chronic diseases, but programmes led by specialists in clinical settings can be too costly for the NHS to deliver at the necessary scale. There is good evidence that primary care referral to commercially available open-group behavioural weight management programmes (like Weight Watchers or Slimming World) is a cost-effective option and 12-week referrals to these programmes are often used in the NHS. However, there is debate about whether a 12 week programme is sufficient to have a long term impact. In the WRAP trial we evaluated whether an extended referral (52 weeks) is more effective and cost-effective over 2 years.
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More about the WRAP Trial
We recruited 1267 adults with overweight and obesity and randomly allocated them to one of three weight loss programmes: brief intervention (a self-help booklet), an open-group behavioural weight management programme (Weight Watchers) for 12 weeks, or the same programme for 52-weeks. Participants were followed up for 2 years, and we collected clinical measurements and self-reported data on psychosocial variables and health resource use at baseline, 3 months, 1 year and 2 years.
At 1 year, both behavioural programmes led to greater weight loss than the brief intervention, but the 52 week programme led to greater weight loss and greater reductions in risk markers for diabetes than the 12 week programme and the brief intervention. Participants in the 52 week programme still had lower weight that the other groups at 2 year follow up.
We modelled the impact of the three programmes over the next 25 years, assuming that everyone regained any weight they had lost by year 5. Over the 25 years, the 12 week programme was predicted to be cost-saving because the initial costs of the programme were outweighed by reductions in diseases incidence and associated healthcare cost. The 52 week programme was more expensive initially, but had greater health benefits than both other groups and was very cost-effective by the usual clinical standards.
Estimates of the long term cost-effectiveness of these programmes is based on assumptions about weight regain in the medium-term. We have recently completed the 5-year follow up study – WRAP UP – to test these assumptions. The data has been analysed and we hope to share the findings soon. WRAP UP will provide the first objective data on 5-year weight trajectories and health outcomes following this type of scalable weight management programme. We will use this data to refine our estimates of the long-term impact on disease incidence and health-care resource use.