Analytical approach:
The economic evaluation used a modelling analysis, the validated CORE diabetes model, to simulate disease progression and the subsequent clinical and economic impact of the two strategies. A lifetime horizon (i.e. 60 years) was adopted. The authors stated that the perspective of the Australian single-payer health care system was adopted.
Effectiveness data:
The baseline characteristics of the patient population were mainly taken from the Australian National Diabetes Information Audit and Benchmarking. Treatment effectiveness (decrease in mean glycosylated haemoglobin, HbA
1c) was based on a published meta-analysis of 52 studies with more than 1,500 patients. Transition probabilities among model health states had already been estimated in the published CORE diabetes model, thus few details of these data were reported. Additional clinical evidence required in the current study appears to have been based on selectively identified studies, including observational cohort studies.
Monetary benefit and utility valuations:
The utility valuations were based on published studies. When published evidence was not available, conservative assumptions were made. No details of the methods used to elicit preferences were provided, although utility weights were reported for each health state.
Measure of benefit:
The summary benefit measures were the life-years (LYs) and quality-adjusted life-years (QALYs). The benefits were discounted at an annual rate of 5%.
Cost data:
The analysis of the costs included insulin administration, concomitant medications and the treatment of diabetes-related complications (e.g. myocardial infarction, angina, stroke, neuropathy). The costs of insulin administration covered the pump, insulin, consumable supplies, self-monitoring of blood glucose, medical assistance with pump initiation, maintenance and operation. The costs and quantities of resources used were derived from published sources, including Australian diagnosis-related groups for all diabetes complications. An annual discount rate of 5% was applied to future costs. The price year was 2006 and the costs were in Australian dollars (AUD).
Analysis of uncertainty:
A number of univariate sensitivity analyses were undertaken to consider the effect of alternative scenarios on treatment effectiveness, hypoglycaemia event rates, change in body mass index, the inclusion of insulin glargine instead of standard insulin for MDI, variations in the discount rates for both costs and benefits, and a different rate of replacement of the insulin pump. A probabilistic sensitivity analysis was also carried out using first-order Monte Carlo simulation. This generated cost-effectiveness acceptability curves.