The analysis was based on a decision-tree model that simulated the patient management for two cohorts: men aged 50 years or older and women aged 60 years or older, both with no known cardiovascular disease. A lifetime horizon was considered and the authors stated that a societal perspective was adopted.
Most of the clinical evidence came from the Justification for the Use of statins in Prevention: an Intervention Trial Evaluating Rosuvastatin (JUPITER) trial (Ridker, et al. 2008, see ‘Other Publications of Related Interest’ below for bibliographic details). Other data were identified by an extensive review of published literature. The baseline characteristics of eligible patients and the treatment effect for rosuvastatin were from the clinical trial. The key input was the efficacy of the test-and-treat strategy, which was defined as the impact of treatment on cardiovascular events (myocardial infarction, unstable angina, revascularisations, stroke, venous thromboembolism, diabetes, elevated liver enzymes, and myopathy). A key assumption was the persistence of treatment efficacy beyond the five-year observation period of the trial. Observational studies were used for the rates of some clinical events without treatment.
Monetary benefit and utility valuations:
The utility values were from the Cost-Effectiveness Analysis Registry and from studies identified by a search of MEDLINE.
Measure of benefit:
Quality-adjusted life-years (QALYs) were the summary benefit measure and they were discounted at an annual rate of 3%.
The economic analysis included the costs of high-sensitivity C-reactive protein test, liver function test, rosuvastatin, treatment of cardiovascular events, and treatment of adverse events. The value of the time for both patients and informal care was considered, using average hourly wages of age-matched US workers. The costs were based on Medicare payments, average wholesale prices, and published reports. The price of branded rosuvastatin was used, until the patent expired seven years into the simulation, when the generic price was used. Hospitalisation data were from the Nationwide Inpatient Sample and other resource use data were from published studies and databases. The costs were in US dollars ($), a 3% annual discount rate was applied, and the price year was 2009.
Analysis of uncertainty:
The uncertainty was investigated in one- and two-way sensitivity analyses on selected inputs, including the efficacy of treatment, the cardiovascular risk (Framingham score), and the drug costs. Published and assumed ranges of values were considered. The cost of care for unrelated medical conditions occurring in additional years of life was considered in an alternative scenario. A probabilistic sensitivity analysis was carried out, using predetermined probability distributions for groups of model inputs; beta distributions for the probabilities and log-normal distributions for the other inputs.