Economic Evaluation of Initial Combination Therapy with Sitagliptin and Metformin Compared to Metformin Monotherapy in the Treatment of Drug-Naive Type 2 Diabetes Patients
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Background: The combination of metformin and DPP 4 inhibitors is believed to have superior health outcomes as compared to metformin alone. However, the cost may be prohibitive and the combination is being considered as a replacement of metformin alone as first line therapy for management of type II diabetes. The comparative cost effectiveness or either treatment is unknown.

Objectives To compare the cost effectiveness of changing the first line therapy in the treatment of type 2 diabetes mellitus form metformin monotherapy to dual therapy of metformin and DPP4 inhibitors in drug naïve patients.

Methodology The study is divided into three parts. The first part will be a local and international price survey, the second part, a key informant interview with staff at Kenyatta National Hospital to identify the key resource input required in the management of diabetic nephropathy and lastly a Markov chain model. The design will be a predictive model based cost effectiveness study. The comparator interventions will be metformn monotherapy and metformin/DPP4 inhibitor dual therapy. Costing will be done from the perspective of the provider and only health care costs will be considered. The time horizon will be 25 years. A macro-ingredient approach will be considered for costing. Effectiveness data will be obtained from literature and the measures of effectiveness will be life expectancy and time to development of diabetic nephropathy. The cost effectiveness ratio and the incremental cost effectiveness ratio will be used to determine how variation in the costs and assumptions about effectiveness will affect the overall cost effectiveness ratio.

Expected benefits This study is expected to provide evidence that it may be more cost effective to initiate newly diagnosed patients on metformin/DPP4 inhibitors. It can be used by policy makers to come to a decision of changing the guideline son treatment of Type 2 Diabetes mellitus in Kenya.