Assessing the cost-effectiveness of type 1 diabetes interventions: the Sheffield type 1 diabetes policy model.

Aims To build a flexible and comprehensive long-term Type1 diabetes mellitus model incorporating the most up-to-date methodologies to allow a number of cost-effectiveness evaluations. Methods This paper describes the conceptual modelling, model implementation and model validation of the Sheffield Type1 Diabetes Policy Model (version1.0), developed through funding by the UK National Institute for Health Research as part of the Dose Adjustment for Normal Eating research programme. The model is an individual patient-level simulation model of Type1 diabetes and it includes long-term microvascular (retinopathy, neuropathy and nephropathy) and macrovascular (myocardial infarction, stroke, revascularization and angina) diabetes-related complications and acute adverse events (severe hypoglycaemia and diabetic ketoacidosis). The occurrence of these diabetes-related complications in the model is linked to simulated individual patient-level risk factors, including HbA(1c), age, duration of diabetes, lipids and blood pressure. Transition probabilities were modelled based on a combination of existing risk functions, published trials, epidemiological studies and individual-level data from the Dose Adjustment for Normal Eating research programme. Results The model takes a lifetime perspective, estimating the impact of interventions on costs, clinical outcomes, survival and quality-adjusted life years. Validation of the model suggested that, for almost all diabetes-related complications predicted, event rates were within 10% of the normalized rates reported in the studies used to build the model. Conclusions The model is highly flexible and has broad potential application to evaluate the Dose Adjustment for Normal Eating research programme, other structured diabetes education programmes and other interventions for Type1 diabetes.