Title: Cost-effectiveness of different levels of uptake of bariatric surgery in a large population. Cohort study and Markov model
Funder: Department of Health (England)

Abstract: Background: There has been a rapid increase in severe and morbid obesity in England. From 1993 to 2010 morbid obesity increased eightfold from 0.2% to 1.6% of all men and nearly tripled from 1.4% to 3.8% of all women. The use of surgical procedures to promote weight loss referred to as bariatric surgery (BS) has emerged as a remarkably effective intervention for severe and morbid obesity. Surgery may result in loss of 20% of body weight by two years with substantial weight loss maintained over 10 years. Surgery is associated with lower incidence of comorbidity compared with non-surgical management and mortality is reduced. Overall the benefits of BS are judged to outweigh the risk of immediate and longer-term complications associated with the procedure and BS has acceptable cost-effectiveness for individuals with severe obesity. The National INstitute for Health and Clinical Excellence (NICE) has recommended that BS may be considered for individuals with body mass index (BMI) >= 40 Kg/m2 or with BMI 35-39 Kg/m2 and comorbidities that have not responded to medical care. Recently the International Diabetes Federation (IDF) has recommended that BS should be considered standard treatment for individuals with diabetes and BMI 35-39 Kg/m2 or with BMI 30-34 and diabetes that is unresponsive to medical therapy. In England about 8000 bariatric surgical procedures are performed each year. Objective: The proposed research aims to estimate the comparative cost-effectiveness of different levels of uptake of bariatric surgery in a population with a high prevalence of severe and morbid obesity. The research will specifically evaluate three intervention strategies.Intervention Strategies: The research will provide evidence of the difference in overall costs and health outcomes (QALYs) of: i) expanding access within existing recognised indications for bariatric surgery as defined by NICE; ii) expanding access by extending the range of recognised indications for bariatric surgery as proposed by the IDF; iii) expanding access with a focus on the distributional consequences of different intervention strategies. This may include facilitating access for specific age-groups socioeconomic groups or giving priority on the basis of gender. Design and Methods: The incremental costs and health benefits of different intervention strategies will be estimated by means of a probabilistic Markov simulation model. Simulation offers a technique that will facilitate estimation of the potential long-term outcomes of different levels of uptake of bariatric surgery within a time-scale that is relevant for commissioners service providers and users. Empirical data inputs to the model will be provided through analysis of data for a large population of obese people registered in primary care derived from the CPRD (Clinical Practice Research Datalink formerly known as General Practice Research Database (GPRD)). Estimates for the clinical effectiveness of bariatric surgery will be derived from updated systematic reviews. The research will take the perspective of the National Health Service. Health service costs will be included. The research will adopt a lifetime time horizon. The primary outcome will be Quality Adjusted Life Years after taking into account the incremental costs of intervention as Net Health Benefits. Patient and Public Involvement: Input from patients and the public will be obtained to calibrate the model outputs against peoples actual experiences of accessing care. Anticipated Outputs: Results from the project will inform decision-makers and stakeholders of the costs and health outcomes of different strategies for facilitating access to BS. The research will produce a methodological tool that can be used to evaluate other clinical and public health interventions for obesity.Dissemination: Main findings will be disseminated through workshops seminars and conferences as well as through project reports and peer-review publications. Concise evidence summaries will be communicated to key decision-makers and stakeholders.


Research activity codes: 7.1 INDIVIDUAL CARE NEEDS;8.1 ORGANISATION AND DELIVERY OF SERVICES
Health categories: GENERIC HEALTH RELEVANCE