A probabilistic decision analytic model, which included both the diagnosis and management of DVTs, was used to evaluate the two prophylactic treatments. The patients’ life-time was the time horizon and the authors reported that the perspective was that of the third-party payer.
The effectiveness data were obtained from a literature review. The criteria applied for the selection of the estimates, the process used to identify the data, and the sources searched were all reported. The main clinical parameters included the rate of proximal DVT and pulmonary embolism (PE) for each prophylactic treatment, the major bleeding events during prophylaxis and during DVT treatment with UH, the death rates due to major bleeding, DVT, PE and PE treatment failure, the sensitivity and specificity of clinical diagnosis of DVT and B-mode ultrasonography, and life expectancy.
Monetary benefit and utility valuations:
Measure of benefit:
The measures of benefit were DVT cases averted and life-years gained (LYG). LYG were discounted using an annual rate of 5%.
The cost categories were the cost of prophylaxis treatment including administration costs, hospitalisation costs including intensive care, and the cost of diagnostic procedures such as chest x-rays and spiral computer tomography. The unit costs, resource use and length of stay data were presented. All costs were based on actual data and were obtained from official sources. They were reported in Canadian dollars (CAD) for the price year of 2003.
Analysis of uncertainty:
A probabilistic analysis was conducted using a Monte Carlo simulation. All the parameters were assigned distributions, with the exception of costs, and these distributions were reported. One- way and two-way sensitivity analyses were performed on both the costs estimates and the discount rate.