Cost-effectiveness of bariatric surgery and non-surgical weight management programmes for adults with severe obesity: a decision analysis model

Abstract

Objectives: To determine the most cost-effective weight management programmes (WMPs) for adults, in England with severe obesity (BMI ≥ 35 kg/m²), who are more at risk of obesity related diseases.

Methods: An economic evaluation of five different WMPs: 1) low intensity (WMP1); 2) very low calorie diets (VLCD) added to WMP1; 3) moderate intensity (WMP2); 4) high intensity (Look AHEAD); and 5) Roux-en-Y gastric bypass (RYGB) surgery, all compared to a baseline scenario representing no WMP. We also compare a VLCD added to WMP1 vs. WMP1 alone. A microsimulation decision analysis model was used to extrapolate the impact of changes in BMI, obtained from a systematic review and meta-analysis of randomised controlled trials (RCTs) of WMPs and bariatric surgery, on long-term risks of obesity related disease, costs, quality adjusted life years (QALYs) and incremental cost-effectiveness ratios (ICERs) measured as incremental cost per QALY gained over a 30-year time horizon from a UK National Health Service (NHS) perspective. Sensitivity analyses explored the impact of long-term weight regain assumptions on results.

Results: RYGB was the most costly intervention but also generated the lowest incidence of obesity related disease and hence the highest QALY gains. Base case ICERs for WMP1, a VLCD added to WMP1, WMP2, Look AHEAD, and RYGB compared to no WMP were £557, £6628, £1540, £23,725 and £10,126 per QALY gained respectively. Adding a VLCD to WMP1 generated an ICER of over £121,000 per QALY compared to WMP1 alone. Sensitivity analysis found that all ICERs were sensitive to the modelled base case, five year post intervention cessation, weight regain assumption.

Conclusions: RYGB surgery was the most effective and cost-effective use of scarce NHS funding resources. However, where fixed healthcare budgets or patient preferences exclude surgery as an option, a standard 12 week behavioural WMP (WMP1) was the next most cost-effective intervention.

Fig. 1. BMI change over time (base-case analysis).

details the modelled BMI change over time. The main figure panel includes all modelled interventions, including surgery. The embedded panel details the BMI change modelled for non-surgical WMPs only. Abbreviations: BMI = Body Mass Index; WMP = Weight Management Programme; VLCD = Very low calorie diet; RYGB = Roux-en-Y gastric bypass surgery.

Fig. 2. Cumulative incidence cases of obesity related disease avoided per 100,000 population with BMI ≥ 35 KG/M2 compared to population trends.

details the cumulative incidence of 12 obesity related disease avoided per 100,000 population with a BMI of 35 and above for each modelled intervention compared to standard care. Abbreviations: BMI = Body Mass Index; WMP = Weight Management Programme; VLCD = Very low calorie diet; RYGB = Roux-en-Y gastric bypass surgery.