Cost-effectiveness of metformin plus vildagliptin compared with metformin plus sulphonylurea for the treatment of patients with type 2 diabetes mellitus: a Portuguese healthcare system perspective

Abstract

Objective:

To evaluate the cost-effectiveness of vildagliptin plus metformin vs generic sulphonylurea plus metformin in patients with type 2 diabetes mellitus, not controlled with metformin, from a Portuguese healthcare system perspective.

Methods:

A cost-effectiveness model was constructed using risk equations from the UK Prospective Diabetes Study Outcomes Model with a 10,000-patient cohort and a lifetime horizon. The model predicted microvascular and macrovascular complications and mortality in yearly cycles. Patients entered the model as metformin monotherapy failures and switched to alternative treatments (metformin plus basal-bolus insulin and subsequently metformin plus intensive insulin) when glycated hemoglobin A1c >7.5% was reached. Baseline patient characteristics and clinical variables were derived from a Portuguese epidemiological study. Cost estimates were based on direct medical costs only. One-way and probabilistic sensitivity analyses were conducted to test the robustness of the model.

Results:

There were fewer non-fatal diabetes-related adverse events (AEs) in patients treated with metformin plus vildagliptin compared with patients treated with metformin plus sulphonylurea (6752 vs 6815). Addition of vildagliptin compared with sulphonylurea led to increased drug acquisition costs but reduced costs of AEs, managing morbidities, and monitoring patients. Treatment with metformin plus vildagliptin yielded a mean per-patient gain of 0.1279 quality-adjusted life years (QALYs) and a mean per-patient increase in total cost of €1161, giving an incremental cost-effectiveness ratio (ICER) of €9072 per QALY. Univariate analyses showed that ICER values were robust and ranged from €4195 to €16,052 per QALY when different parameters were varied.

Limitations:

The model excluded several diabetes-related morbidities, such as peripheral neuropathy and ulceration, and did not model second events. Patients were presumed to enter the model with no diabetes-related complications.

Conclusion:

Treatment with metformin plus vildagliptin compared with metformin plus sulphonylurea is expected to result in a lower incidence of diabetes-related AEs and to be a cost-effective treatment strategy.

Keywords::

• Diabetes mellitus
• Vildagliptin
• Cost-effectiveness
• Portugal
• Sulphonylurea
• Metformin

Transparency

Declaration of funding

Supported by funding from Novartis Pharma AG. The funding organization provided feedback on the design of the model and the inputs/sources used in the model. The funding organization also reviewed the manuscript.

Declaration of financial/other relationships

D. Viriato and R. Viana are employees of Novartis Farma SA. F. Calado, J.-B. Gruenberger and S. H. Ong are employees of Novartis Pharma AG. S. Johal is an employee of HERON Commercialization – A PAREXEL Company, a consulting company that provides services to several pharmaceutical companies, including Novartis Farma SA and Novartis Pharma AG, and received funding to complete this analysis. D. Carvalho and J. Silva-Nunes have received consulting/speaking fees from Novartis Farma SA.

Acknowledgments

Nick Rusbridge at HERON Commercialization – A PAREXEL Company provided editorial support in the preparation of this manuscript, funded by Novartis Pharma AG.