Cost-effectiveness of an integrated lifestyle intervention for obesity in southern Italy: a model-based simulation of costs, health outcomes and gastrointestinal cancer burden

We assessed the cost-effectiveness of a publicly funded lifestyle programme (supervised exercise and nutritional counselling) for adults with obesity (BMI 30.0–34.9 kg/m 2 ) in Southern Italy and its projected effect on colorectal and hepatocellular cancer burden. A deterministic cohort state-transition (Markov-type) model with annual cycles simulated 19,000 treatment episodes delivered to 16,736 adults over 20 years, compared with standard of care from societal and payer perspectives. Costs (2024 euros) and QALYs were discounted at 3%. Uncertainty was assessed by one-way and break-even analyses, a 10,000-iteration probabilistic analysis, and an extreme scenario compounding reduced efficacy, higher relapse and a 6% discount rate. The programme yielded 1,354.50 incremental QALYs (0.081 per treated adult) at a net societal cost of €30.06 million: ICER €22,192/QALY societal and €25,987/QALY payer, net monetary benefit €10.58 million at €30,000/QALY. Assuming that sustained weight loss reduced 50% of the excess cancer risk associated with obesity, the model projected a 1.44% relative reduction in incidence (7.2 cases avoided, 95% central range 2.1–16.3, €123,000 in avoided cancer care). The intervention was cost-effective in 67.7% of draws; under the extreme scenario the ICER rose to €183,641/QALY (probability <0.1%). Cost-effectiveness is conditional on sustained adherence and contained relapse rather than inherent.