(Cost-)effectiveness of a combined lifestyle intervention integrated into standard care for low back pain compared to usual care for people with persistent non-specific low back pain who are overweight or obese: Protocol for a randomised controlled trial with parallel economic and process evaluations (Back2Health)

BACKGROUND: Low back pain is often influenced by unhealthy lifestyle factors, such as physical inactivity, poor sleep, unhealthy diet, and excess weight. Despite their impact, these factors are rarely addressed in routine care for non-specific low back pain. In the Netherlands, adults with overweight or obesity can access a combined lifestyle intervention targeting physical activity, diet, sleep and stress. Integrating this intervention into standard care for non-specific low back pain may improve patient outcomes. METHODS: The Back2Health study is a two-armed randomised controlled trial with parallel economic and process evaluations evaluating the (cost-)effectiveness of an integrated lifestyle intervention versus usual care on physical functioning and physical activity over 36 months in patients with persistent non-specific low back pain and overweight or obesity. In total, 318 adults will be recruited from Dutch hospitals and randomised (1:1) to either the integrated lifestyle intervention, delivered by physiotherapists trained as lifestyle coaches, or usual care.Co-primary outcomes are physical functioning and physical activity (steps/day) over 36 months. Secondary outcomes include pain intensity, systemic inflammation markers, sleep, and diet. Participants complete questionnaires every 3-6 months and attend in-person physical assessments at five timepoints. Data will be analysed according to both 'intention-to-treat' and 'per-protocol' principles. Additionally, a process and economic evaluation will be performed. ETHICS AND DISSEMINATION: The study protocol was approved by a medical ethics committee (METC Brabant: NL85373.028.23). Results will be published in peer-reviewed journals and presented at (inter)national conferences. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov (NCT06594796).