Evaluation of a group-based behavioural intervention (PROGROUP) versus usual care for weight management in adults with severe obesity: protocol for a randomised controlled trial with cost-consequence analysis and primary care implementation study.

Abstract

Approximately 15 million people in the UK live with obesity and at least 5 million of these are people with severe obesity (PWSO). Severe obesity significantly compromises health, well-being and quality of life and reduces life expectancy. These adverse outcomes are prevented or ameliorated by weight loss, for which sustained behavioural change is the cornerstone of treatment. Several studies suggest the potential of group-based intervention in Specialist Weight Management Services (SWMS), but PWSO remain underrepresented in research, and evidence on optimal design and outcomes is limited. The success of the PROGROUP feasibility randomised controlled trial (RCT) (ISRCTN22088800) informed the development of this study and additional adjustments have been made in response to the rollout of obesity management medication in the National Health Service (NHS). This study aims to assess the effectiveness and cost-effectiveness of PROGROUP in SWMS and primary care. The RCT will be conducted in SWMS, alongside an implementation study in primary care. The RCT will recruit cohorts of 30 participants to be randomised 1:1 within-cohort to PROGROUP (intervention) or usual care (control). The implementation arm will recruit cohorts of 15 to PROGROUP. The primary objectives for the study are to undertake a process evaluation and economic evaluation of PROGROUP in the RCT and to assess its implementation in primary care. Baseline data and outcome differences at 6 months will be analysed. These will include weight, other clinical measures and patient-reported outcomes, including social and life-satisfaction measures. This study is approved by an NHS Research Ethics Committee (REC reference: 23/WS/0101). Results will be reported in a manuscript that will be submitted to a peer-reviewed medical journal as open access. A lay summary of the findings will be published online, and participants and sites will be signposted to this. ISRCTN13721429.