Incremental Cost-Effectiveness Ratios (ICERs) and Revised Metformin Cost-Effectiveness Conclusions in the Diabetes Prevention Program/ Diabetes Prevention Program Outcomes Study.

Introduction: Based on previously published US Diabetes Prevention Program (DPP) cost-effectiveness analyses (CEAs), metformin continues to be promoted as "cost-effective." We reviewed a 10-year CEA to assess this. Treatment alternatives included placebo, branded metformin and individual lifestyle modification. Following the original CEA, we added group lifestyle as a modeled alternative. Methods: Original published data were taken as given and re-analyzed according to accepted principles for calculating incremental cost-effectiveness ratios (ICERs). With more than 2 treatments, these require attention to the rankings of interventions according to cost or effect prior to stipulating appropriate ICERs to calculate. Results: With appropriate ICER calculations, metformin was not cost-effective. Net Loss calculations indicated substantial costs/health losses to using metformin instead of the optimal lifestyle alternative in response to metformin having been confusingly labeled "cost-saving" in the original CEA. Conclusions: The original DPP CEA, subsequent analyses and citations of such analyses continue to conclude that both metformin and lifestyle modification are cost-effective in diabetes prevention. However, using metformin implies substantial costs and health losses compared to the cost-effective lifestyle modification. It may be that metformin has a role in cost-effective diabetes prevention, but this has yet to be shown based on DPP data.