Modeling the economics of prevention

Abstract

Cardiovascular disease, particularly coronary heart disease and stroke, is the most common cause of death world wide, with a prevalence that is expected to increase. The consequences of the modern lifestyle such as obesity and physical inactivity are also associated with the risk of developing diabetes, another risk factor for the development of cardiovascular disease. Patients who have developed cardiovascular disease are also of high risk of subsequent events. Measures to prevent disease would lead to health gains in the population, but such measures come at a cost. As health care systems have come under increasing economic strain, it is necessary to carefully assess the economic consequences of new interventions to see if they represent money well spent.

The purpose of this thesis was to explore the use of different epidemiological materials when conducting economic evaluations. This was done by performing economic evaluations based on four different trials: two in primary prevention and two in secondary prevention.

In primary prevention, a program of diet and/or exercise to prevent cardiovascular disease directed towards 60 year old men and an intensive lifestyle intervention program to prevent the development of type 2 diabetes mellitus in patients with impaired glucose tolerance was evaluated. In secondary prevention, the use of clopidogrel in addition to acetylsalicylic acid was evaluated in patients with acute coronary syndromes and in the subset of patients undergoing percutaneous coronary intervention.

To perform the economic evaluation, computer simulation models were constructed. These models used data from the clinical trials and from different epidemiological data sources to estimate the risk of events in different populations and to extrapolate the effects on mortality caused by the end-points used in the clinical trials. Where surrogate endpoints (such as blood pressure reduction) were used, risk-functions based on epidemiological data were used to translate these results into cardiovascular events. In the primary prevention studies, a large population based cohort was used to get good estimates on the distribution of risk factors.

In all four cases, the interventions were found to be cost-effective and in one case (that of prevention of diabetes) even cost-saving to the health care payer. It was found that epidemiological data can be used in several ways in the economic evaluations, and that the intended use puts different demands on the underlying data.