Comparative cost-effectiveness of metformin-based dual therapies associated with risk of cardiovascular diseases among Chinese patients with type 2 diabetes: Evidence from a population-based national cohort in Taiwan

•Chinese patients with type 2 diabetes using metformin and sulfonylureas dual therapy had relatively higher risk of cardiovascular diseases in the long-run, consequently higher healthcare spending. Among thiazolidinediones, metformin plus rosiglitazone had lower risk of cardiovascular diseases, as compared to metformin plus pioglitazone.•In the present conditions in Taiwan, for cardiovascular disease risk, cost-effectiveness analysis indicated that metformin plus glinides was least expensive and most effective, while metformin plus pioglitazone may be more cost-effective especially for the elderly or those with severe diabetic complications.

ObjectiveTo assess the cost-effectiveness of metformin-based dual therapies associated with cardiovascular disease (CVD) risk in a Chinese population with type 2 diabetes.MethodsWe utilized Taiwan's National Health Insurance Research Database (NHIRD) 1997-2011, which is derived from the claims of National Health Insurance, a mandatory-enrollment single-payer system that covers over 99% of Taiwan's population. Four metformin-based dual therapy cohorts were used, namely a reference group of metformin plus sulfonylureas (Metformin-SU) and metformin plus acarbose, metformin plus thiazolidinediones (Metformin-TZD), and metformin plus glinides (Metformin-glinides). Using propensity scores, each subject in a comparison cohort was 1:1 matched to a referent. The effectiveness outcome was CVD risk. Only direct medical costs were included. The Markov chain model was applied to project lifetime outcomes, discounted at 3% per annum. The bootstrapping technique was performed to assess uncertainty in analysis.ResultsMetformin-glinides was most cost-effective in the base-case analysis; Metformin-glinides saved $194 USD for one percentage point of reduction in CVD risk, as compared to Metformin-SU. However, for the elderly or those with severe diabetic complications, Metformin-TZD, especially pioglitazone, was more suitable; as compared to Metformin-SU, Metformin-TZD saved $840.1 USD per percentage point of reduction in CVD risk. Among TZDs, Metformin-pioglitazone saved $1831.5 USD per percentage point of associated CVD risk reduction, as compared to Metformin-rosiglitazone.ConclusionsWhen CVD is considered an important clinical outcome, Metformin-pioglitazone is cost-effective, in particular for the elderly and those with severe diabetic complications.