A cost-effectiveness analysis of pioglitazone plus metformin compared with rosiglitazone plus metformin from a third-party payer perspective in the US.

OBJECTIVE: The long-term cost-effectiveness of using pioglitazone plus metformin (Actoplusmet dagger) compared with rosiglitazone plus metformin (Avandamet double dagger) in treating type 2 diabetes (T2DM) was assessed from a US third-party payer perspective.

RESEARCH DESIGN AND METHODS: Clinical efficacy (change in HbA(1c) and lipids) and baseline cohort parameters were extracted from a 12-month, randomized clinical trial (Derosa et al., 2006) evaluating the efficacy and tolerability of pioglitazone versus rosiglitazone, both in addition to metformin, in adult T2DM patients with insufficient glucose control (n = 96). A Markov-based model was used to project clinical and economic outcomes over 35 years, discounted at 3% per annum. Costs for complications were taken from published sources. Base-case assumptions were assessed through several sensitivity analyses.

MAIN OUTCOME MEASURES: Outcomes included incremental life-years, quality-adjusted life-years (QALYs), total direct medical costs, cumulative incidence of complications and associated costs, and incremental cost-effectiveness ratios (ICERs).

RESULTS: Compared to rosiglitazone plus metformin, pioglitazone plus metformin was projected to result in a modest improvement in 0.187 quality-adjusted life-years. Over patients' lifetimes, total direct medical costs were projected to be marginally lower with pioglitazone plus metformin (difference -$526.), largely due to reduced CVD complication costs. While costs were higher among renal, ulcer/amputation/neuropathy, and eye complications in the pioglitazone plus metformin group, the cost savings for CVD complications outweighed their economic impact. Pioglitazone plus metformin was found to be a dominant long-term treatment strategy in the US compared to rosiglitazone plus metformin. Sensitivity analyses showed findings to be robust under almost all scenarios, including short-term time horizons, 6% discounting, removal of individual lipid parameters, and modifications of patient cohort to more closely represent a US T2DM population. Pioglitazone plus metformin was no longer dominant with 0% discounting, with 25% reduction in its HbA(1c) effects, or with a 15% increase in its acquisition price.

CONCLUSIONS: Under a range of assumptions and study limitations around cohorts, clinical effects, and treatment patterns, this long-term analysis showed that pioglitazone plus metformin, when compared to rosiglitazone plus metformin, was a dominant treatment strategy within the US payer setting. Results were driven by the combination of modest differences in QALYs and modest savings in total complication costs over 35 years.