Cost-effectiveness of dipeptidyl peptidase-4 inhibitor monotherapy in elderly type 2 diabetes patients in Thailand

Unchalee Permsuwan,1 Piyameth Dilokthornsakul,2 Surasak Saokaew,2–4 Kednapa Thavorn,5–7 Nathorn Chaiyakunapruk2,4,8,9 1Faculty of Pharmacy Chiang Mai University, Chiang Mai, 2Center of Pharmaceutical Outcomes Research, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok, 3Center of Health Outcomes Research and Therapeutic Safety, School of Pharmaceutical Sciences, University of Phayao, Phayao, Thailand; 4School of Pharmacy, Monash University Malaysia, Sunway, Malaysia; 5Ottawa Hospital Research Institute, The Ottawa Hospital, 6School of Epidemiology, Public Health and Preventive Medicine, Faculty of Medicine, University of Ottawa, Ottawa, 7Institute for Clinical and Evaluative Sciences, Toronto, ON, Canada; 8School of Population Health, The University of Queensland, Brisbane, QLD, Australia; 9School of Pharmacy, University of Wisconsin–Madison, Madison, WI, USA Background: The management of type 2 diabetes mellitus (T2DM) in elderly population poses many challenges. Dipeptidyl peptidase-4 (DPP-4) inhibitors show particular promise due to excellent tolerability profiles, low risk of hypoglycemia, and little effect on body weight. This study evaluated, from the health care system’s perspective, the long-term cost-effectiveness of DPP-4 inhibitor monotherapy vs metformin and sulfonylurea (SFU) monotherapy in Thai elderly T2DM patients. Methods: The clinical efficacy was estimated from a systematic review and meta-analysis. Baseline cohort characteristics and cost parameters were obtained from published studies and hospital databases in Thailand. A validated IMS CORE Diabetes Model version 8.5 was used to project clinical and economic outcomes over a lifetime horizon using a 3% annual discount rate. Costs were expressed in 2014 Thai Baht (THB) (US dollar value). Incremental cost-effectiveness ratios were calculated. Base-case assumptions were assessed through several sensitivity analyses. Results: For treating elderly T2DM patients, DPP-4 inhibitors were more expensive and less effective, ie, a dominated strategy, than the metformin monotherapy. Compared with SFU, treatment with DPP-4 inhibitors gained 0.031 more quality-adjusted life years (QALYs) at a total cost incurred over THB113,701 or US$3,449.67, resulting in an incremental cost-effectiveness ratio of THB3.63 million or US$110,133.50 per QALY. At the acceptable Thai ceiling threshold of THB160,000/QALY (US$4,854.37/QALY), DPP-4 inhibitors were not a cost-effective treatment. Conclusion: DPP-4 inhibitor monotherapy is not a cost-effective treatment for elderly T2DM patients compared with metformin monotherapy and SFU monotherapy, given current resource constraints in Thailand. Keywords: cost-effectiveness analysis, DPP-4 inhibitor, elderly, type 2 diabetes, Thailan