Lifetime Health Consequences and Cost-effectiveness of Rosiglitazone in Combination with Metformin for the Treatment of Type 2 Diabetes in Spain

Abstract

To assess the lifetime diabetes health consequences and cost-effectiveness in Spain of rosiglitazone in combination with metformin for the treatment of type 2 diabetes in overweight and obese patients failing to maintain glycaemic control with metformin monotherapy compared with conventional care of metformin in combination with either sulfonylureas or bedtime insulin. The Diabetes Decision Analysis of Cost--Type 2 was adapted for clinical practice and healthcare funding in Spain, and was calibrated with Spanish epidemiological, healthcare resource use and cost data, taking the perspective of the Spanish National Health System. The model simulates lifetime treatment histories, complications and consequences of type 2 diabetes, and associated health outcomes and costs for age and sex-matched cohorts of 1000 overweight and obese patients. The primary health outcome measures compared are glycaemic control, time to insulin, incidence and prevalence of coronary heart disease, stroke, clinical nephropathy, ulceration and amputation, and severe visual loss, and incremental life-years and quality-adjusted life-years (QALYs). Rosiglitazone in combination with metformin produces better glycaemic control than conventional care of metformin in combination with either sulfonylureas or bedtime insulin in most patients, and extends the viability of combination therapy by between 6 and 13 years before requiring insulin. Rosiglitazone patients have a longer life expectancy, gaining between 106 and 175 additional life-years per 1000 patients, experience fewer episodes of coronary disease and clinical nephropathy, and live for longer periods free of complications. The improvements in morbidity and mortality are projected to yield between 134 and 238 additional QALY per 1000 patients over their lifetime. Discounted incremental cost-effectiveness ratios range from euro 9406 to euro 23,514 per QALY gained. The model predicts that rosiglitazone in combination with metformin is a cost-effective intervention for the treatment of both overweight and obese patients with type 2 diabetes when compared with conventional care in Spain.