Evaluation of the costs and outcomes from changes in risk factors in type 2 diabetes using the Cardiff stochastic simulation cost-utility model (DiabForecaster)

Abstract

Aims: The aim of this study was to determine the mean costs and outcomes associated with modifiable risk factors in patients with type 2 diabetes and to determine equivalent changes to these risk factors in terms of financial costs and health outcomes.

Methods: The Cardiff Stochastic Simulation Cost-Utility Model (DiabForecaster), which evolved from the Eastman model, was used to follow a cohort of 10 000 patients over 20 years.

Results: Costs were affected most significantly by changes in the total cholesterol to HDL cholesterol (Total-C:HDL-C) ratio and in HbA(1c). Unit increases in Total-C:HDL-C increased discounted costs by pound 200 per patient; for ratios > 8 units, unit increases led to cost increases of pound 300 per patient. Unit increases in HbA(1c) increased per patient discounted costs from pound 200 (5-6%) up to pound 2900 (10-11%). Similar patterns were observed for QALYs. Estimates of equivalence showed that a 1% reduction in HbA(1c) was equivalent to an 0.4 increment in QALYs, which was equivalent to a reduction of 44 mmHg in SBP, 18.2 mg/dL in HDL, 100 mg/dL in total cholesterol or 1.8 units of Total-C:HDL-C ratio. A 1% reduction in HbA(1c) was also equivalent to pound 108 less cost, which was equivalent to a 13.0 mmHg decrease in SBP or a 0.57 unit decrease in the Total-C:HDL-C ratio.

Conclusions: This model provides reliable utility estimates for diabetic complications and may eliminate uncertainty in cost-effectiveness analyses of treatment. These data also provide a novel way of comparing the value of treatments that have multiple effects.