effectiveness analysis prevention of type 2 diabetes in adults : cost Different strategies for screening and

Objective To compare four potential screening strategies, and subsequent interventions, for the prevention and treatment of type 2 diabetes: (a) screening for type 2 diabetes to enable early detection and treatment, (b) screening for type 2 diabetes and impaired glucose tolerance, intervening with lifestyle interventions in those with a diagnosis of impaired glucose tolerance to delay or prevent diabetes, (c) as for (b) but with pharmacological interventions, and (d) no screening. DesignCost effectivenessanalysis basedondevelopment and evaluation of probabilistic, comprehensive economic decision analytic model, from screening to death. Setting A hypothetical population, aged 45 at time of screening, with above average risk of diabetes. Data sourcesPublishedclinical trials andepidemiological studies retrieved fromelectronicbibliographicdatabases; supplementary data obtained from the Department of Health statistics for England and Wales, the screening those at risk (STAR) study, and the Leicester divisionof the ADDITION study. Methods A hybrid decision tree/Markov model was developed to simulate the long term effects of each screening strategy, in terms of both clinical and cost effectiveness outcomes. The base case model assumed a 50 year time horizon with discounting of both costs and benefits at 3.5%. Sensitivity analyses were carried out to investigate assumptions of the model and to identify which model inputs had most impact on the results. Results Estimated costs for each quality adjusted life year (QALY) gained (discounted at 3.5% a year for both costs and benefits) were £14150 (€17560; $27860) for screening for type 2 diabetes, £6242 for screening for diabetes and impaired glucose tolerance followed by lifestyle interventions, and £7023 for screening for diabetes and impaired glucose tolerance followed by pharmacological interventions, all compared with no screening. At a willingness-to-pay threshold of £20000 the probability of the intervention being cost effectivewas 49%, 93%, and 85% for each of the active screening strategies respectively. Conclusions Screening for type 2 diabetes and impaired glucose tolerance, with appropriate intervention for those with impaired glucose tolerance, in an above average risk population aged 45, seems to be cost effective. The cost effectiveness of a policy of screening for diabetes alone, which offered no intervention to those with impaired glucose tolerance, is still uncertain. INTRODUCTION In 2000, an estimated 171 million people worldwide had diabetes and numbers are projected to double by 2030. Life expectancy in people with diabetes might be shortenedbyasmuchas15years.Currently there is no systematic or structured screening policy for type 2 diabetes in the United Kingdom, though some general guidance has recently been issued by the National Screening Committee. One approach to screening would be to screen only for type 2 diabetes, which will allow for early diagnosis and treatment. This might be important as early detection and treatment could prevent future associated microvascular and macrovascular complications. An estimated 50% of people with diabetes are currently undiagnosed, and at presentation around 20-30% have already developed complications. An alternative screening approach would be to lower the threshold of the screening test and to screen for impaired glucose tolerance and type 2 diabetes together. As well as allowing for earlier diagnosis of type 2 diabetes, interventions can be administered to those identified with impaired glucose tolerance to attempt to delay the onset of type 2 diabetes. A recent systematic review andmeta-analysis of intervention trials for prevention of type 2 diabetes foundboth lifestyle andpharmacological interventions significantly reduced the risk of type 2 diabetes in people with impaired glucose tolerance. As no definitive trials have examined the effectiveness of screening for type 2 diabetes or impaired glucose tolerance, 8 assessment of such policies has so far been conducted through simulation studies. Several decision models have been compiled that have assessed either the clinical and cost effectiveness of Centre for Biostatistics and Genetic Epidemiology, Department of Health Sciences, University of Leicester, Leicester LE1 7RH Department of Cardiovascular Sciences, University of Leicester Division of General Practice and Primary Health Care, Department of Health Sciences, University of Leicester Correspondence to: C L Gillies clg13@le.ac.uk doi:10.1136/bmj.39545.585289.25 BMJ | ONLINE FIRST | bmj.com page 1 of 11 on 28 April 2008 bmj.com Downloaded from