Analytical approach:
A Markov model was constructed to synthesise data from published observational and experimental studies and assumptions made by the authors. The analysis covered eight years and the authors stated that a health care payer’s perspective was taken.
Effectiveness data:
A literature review, using the MEDLINE and CINAHL databases, was undertaken. Studies up to 2006 were selected if they reported relevant disease transition rates or they compared ACE inhibitors with placebo. The clinical estimates included cardiovascular disease (CVD) events, dialysis, all-cause mortality, and a composite endpoint of these three measures. The transition probabilities for nephropathy progression came from randomised trials, that compared ACE inhibitors with placebo, and the evidence on CVD events was abstracted from two prospective cohort studies. The clinical inputs were fully reported and referenced.
Monetary benefit and utility valuations:
Not relevant.
Measure of benefit:
The measures of benefit were CVD events prevented, lives saved, and dialysis cases prevented.
Cost data:
The direct medical costs were those of the ACE inhibitors, CVD events including myocardial infarction, ischaemic stroke, angina, and microvascular or macrovascular complications. Average wholesale prices were used for the ACE inhibitors. The data on resources used and their values were abstracted from previous studies, one of which included 12,000 patients with diabetes and lasted for nine years (Brown, et al. 1999, see ‘Other Publications of Related Interest’ below for bibliographic details). The annual costs were presented and were clearly referenced. All costs were presented in 2005 US dollars ($) and adjusted using the medical component of the US Consumer Price Index.
Analysis of uncertainty:
The parameter uncertainty was addressed using one-way sensitivity analyses on the nephropathy progression rates, ACE inhibition rates, and costs, by varying them by ±25%. Two-way analyses on the progression rates and low- or high-cost ACE inhibitor combinations were also performed and the results were presented in a table.