Analytical approach:
This economic evaluation was based on a published Markov model (Palmer, et al. 2004, see 'Other Publications of Related Interest' below for bibliographic details), with seven health states to stimulate the progression from microalbuminuria to ESRD and treatment with dialysis. The time horizon was 25 years from a baseline age of 58 years. The authors stated that the UK National Health Service (NHS) perspective was adopted.
Effectiveness data:
The data on treatment efficacy and for transition probabilities were based mainly on two clinical trials: the Irbesartan in Reduction of Microalbuminuria-2 (IRMA-2) trial and the Irbesartan in Diabetic Nephropathy Trial (IDNT). Other data came from national registries and other published sources. The mortalities were country-specific. The key clinical inputs were the transition rates for ESRD with and without irbesartan.
Monetary benefit and utility valuations:
Not relevant.
Measure of benefit:
The primary benefit measures were life expectancy and the number of life-years gained with the treatments. A 3.5% annual discount rate was applied to future benefits. The cumulative incidence of ESRD and the number of years the patients lived free of ESRD, were also reported.
Cost data:
The economic analysis focused on the incremental costs of irbesartan treatment and ESRD treatment, including dialysis or transplant and hospitalisation for comorbidities and complications. The costs of concomitant medications were assumed to be similar between treatments and were not included. The costs were derived from published literature and NHS databases. They were expressed in UK pounds sterling (£), for the price year 2002. All costs were discounted at a rate of 3.5%.
Analysis of uncertainty:
A second-order Monte Carlo simulation was used to generate the mean, standard deviation, and confidence intervals for the costs and benefits. Further sensitivity analyses were carried out by varying: the levels of urinary albumin excretion at which patients entered the state of advanced overt nephropathy; the transition probabilities between disease states; and the annual probabilities of death.