Cost-effectiveness of sitagliptin-based treatment regimens in European patients with type 2 diabetes and haemoglobin A1c above target on metformin monotherapy

Objective:  Sitagliptin is a novel oral incretin enhancer that acts by inhibiting the dipeptidyl peptidase 4 enzyme and is indicated in Europe as a treatment adjunct to metformin (MF), sulphonylurea (SU), MF plus SU and diet and exercise, in the management of type 2 diabetes mellitus. The objective of the current analysis was to evaluate the cost-effectiveness of adding sitagliptin to the regimens of patients with haemoglobin A1c (HbA1C) above the International Diabetes Federation goal (6.5%) while on MF in six European countries: Austria, Finland, Portugal, Scotland (United Kingdom), Spain and Sweden. Methods:  A discrete event simulation model, which employed the United Kingdom Prospective Diabetes Study (UKPDS) Outcomes Model risk equations for predicting risks of diabetes-related complication, was used. Lifetime costs and benefits were projected for alternative treatment strategies of adding sitagliptin, compared with adding rosiglitazone or a SU to MF in patients not at HbA1C goal on MF monotherapy. Changes in HbA1C as well as side effects associated with these different treatment strategies were based on clinical trial data. Mean baseline values from local epidemiologic studies involving patients with type 2 diabetes not at HbA1C goal on MF monotherapy were included in the current analysis. Costs of medications, side effects and direct costs of diabetes-related complications were based on country-specific data. UKPDS-based disutility weights associated with diabetes complications were incorporated. Disutilities associated with medication side effects were based on published data. All future costs and benefits were discounted according to local guidelines on cost-effectiveness analysis. One-way sensitivity analyses were conducted by varying key input parameters. Findings:  The discounted incremental cost-effectiveness ratios (ICER) associated with the addition of sitagliptin to MF, compared with adding rosiglitazone, in the different countries analysed ranged from treatment with sitagliptin being dominant (cost saving with improved health outcome) to its being cost-effective [€4,766 per quality-adjusted life year (QALY)]. Treatment with sitagliptin added to MF was cost-effective compared with adding a SU, with discounted ICER values ranging from €5949/QALY to €20 350/QALY across countries. Sensitivity analyses showed that these results were robust to changes in input parameters, including clinical efficacy, costs and utility weights for both diabetes-related complications and hypoglycaemia. Conclusions:  Compared with adding rosiglitazone or a SU to MF, adding sitagliptin to MF is projected to be either cost saving or cost-effective for patients with type 2 diabetes who are not at HbA1C goal on MF.