The analysis was based on a decision tree model with a four-year time horizon. The authors stated that the analysis took the perspective of the health care financer such as a Health Insurance Plan.
Clinical inputs were based on the published literature and expert opinion. The authors stated that randomised clinical trials were on progress at the time of the study but no results were available. It appeared that observational studies were used to obtain clinical inputs for the decision model. Rates of stroke or transient ischaemic attack (TIA) were key inputs of the model.
Monetary benefit and utility valuations:
Utility valuations were taken from a published review supplemented with data obtained by the authors using the visual analogue scale.
Measure of benefit:
Quality-adjusted life-years (QALYs) were used as the summary benefit measure and were discounted at an annual rate of 3%.
The economic analysis included the costs of aspirin, anticoagulants, PDC of PFO and management of recurrence. Drug costs were taken from a single institution. Hospital costs were based on an official database of medical services costs. Costs were in Argentine pesos (ARS). A 3% annual discount rate was applied.
Analysis of uncertainty:
A deterministic approach was used to identify the most influential inputs plotted in a tornado diagram.