Analytical approach:
The authors constructed a decision analytic model (decision tree) to compare the cost-effectiveness of the four diagnostic strategies. The time horizon was three months and the authors reported that the perspective was that of the health care system.
Effectiveness data:
The effectiveness data were mainly obtained from two prospective multi-centre outcome studies and were combined by the authors. Some data were derived from peer-reviewed publications by means of a systematic literature review. The main clinical parameters included the sensitivity and specificity of the tests for each age group; mortality due to anticoagulant treatment, helical computed tomography, and angiography; and risk of major haemorrhage due to anticoagulant treatment.
Monetary benefit and utility valuations:
The utility values were obtained from published studies. The instruments and methods used to derive these utilities were not reported.
Measure of benefit:
Initially, three-month quality-adjusted expected survival was the measure of benefit. Based on predefined criteria, the therapeutic equivalence of the four strategies was demonstrated and only the costs were analysed.
Cost data:
The cost categories included the diagnostic tests, anticoagulant and coumarin treatment, in-patient and out-patient treatment, and major bleeding complications. These costs were obtained from the authors’ setting and from other settings, which were the USA, Canada, and France. All costs were reported in US dollars ($) for the price year 2006.
Analysis of uncertainty:
The parameter uncertainty was investigated using one- and two-way sensitivity analyses, varying the estimates of costs, sensitivity and specificity values of the diagnostic tests, and mortality. The ranges over which the parameters were varied were reported.