Economic evaluation of orlistat in overweight and obese patients with type 2 diabetes mellitus

Objective: To estimate the economic value of pharmacological treatment of type 2 diabetes mellitus in overweight and obese patients using orlistat in addition to standard diabetes therapy (i.e., a sulphonlyurea, metformin or insulin) and weight management strategies as compared with standard diabetes therapy and weight management strategies alone in a US-based healthcare setting. The perspective of the study was from the viewpoint of a US healthcare provider. Design and setting: Markov state transition model simulating diabetes-related complications and mortality for a period of 11 years. Patients were modelled to continue orlistat therapy for a 52-week period, assuming a 3-year period of weight regain where after 3 years bodyweight would match that of the placebo group. The impact of orlistat on glycosylated haemoglobin (HbA(1c)) values was evaluated directly using data from four randomised, placebo-controlled, 1-year trials of orlistat in overweight or obese adults with type 2 diabetes who also received standard diabetes phan-nacotherapy and intensive lifestyle modification. Incidence rates of micro- and macrovascular complications associated with type 2 diabetes and the estimated relative reduction in incidence rates associated with a decrease in mean updated HbA(1c) values were derived from the United Kingdom Prospective Diabetes Study (UKPDS) estimates for a reference population of male patients, 52 years of age. US cost estimates were derived from published sources and presented in 2001 US dollars. Discounting of 3% was applied. Probabilistic sensitivity analysis was applied to evaluate the robustness of the results of the persistence of the effect of orlistat after treatment. Main outcome measures: Average costs and event-free life-years gained during the 11-year period expressed as the incremental costs divided by the incremental gain in life expectancy. Results: Treatment with orlistat, 120mg three times daily, increased event-free life expectancy by 0.13 years over an 11-year period. Average treatment costs were estimated to be $US19 987 in the orlistat group compared with $US 18 865 in the group that received diabetes medication and weight management alone. This translated into a cost-effectiveness ratio of $US8327 per event-free life-year gained.