Title:
The cost-effectiveness of primary care referral to a UK commercial weight loss programme.

Abstract:
Primary care referral to commercial weight loss programmes that follow best practice is included in current UK guidance on the management of adult obesity. This study investigated whether such a programme was cost-effective compared with usual care. A decision-analytical Markov model was developed to estimate the lifetime costs and benefits of the referral programme compared with usual care and enable a cost-utility analysis. The model cohort transited between body mass index classifications and type 2 diabetes, stroke and myocardial infarction (MI) with risk, cost and effect parameter values taken from published literature. The cost per incremental quality-adjusted life year (QALY) was calculated. Extensive deterministic and scenario sensitivity analyses and probabilistic sensitivity analyses (PSA) were conducted. At 12 months, the incremental cost-effectiveness ratio was £6906, indicating that programme referral was cost-effective. Over a lifetime, referral to the commercial programme was dominant as it led to a cost saving of £924 and conferred incremental benefit (0.22 QALY) over usual care. Model simulations estimated lower lifetime rates of type 2 diabetes, stroke and MI as a result of the weight loss achieved. The results were robust to extensive sensitivity analyses. The PSA indicated that programme referral had a 68% chance of being cost-effective at a willingness to pay per incremental QALY threshold of £20,000. Referral to the programme dominated usual care, being both cheaper and more effective. These results compare favourably with economic evaluations of other obesity interventions and add to a growing evidence base on the cost-effectiveness of commercial weight loss providers and practices.