A method for comparing and combining cost-of-illness studies: an example from cardiovascular disease

This paper describes a method for comparing and combining the results of various cost-of-illness (COI) studies. The method consists of seven steps: identify the study design; stratify according to the cost components; create concatenated cost components; adjust for inflation; adjust for population growth; compare cost estimates; and combine cost estimates. Based on this method, and using published data from 1986, 1993 and 1994, the cost of cardiovascular disease was estimated to be $20.1 billion in Canada in 2000, or $653 per person per year. One cost component, premature mortality, was found to have significantly decreased over time. The method described in this paper is sophisticated yet simple to use, and provides an efficient way to update, compare and combine cost estimates. By analyzing changes in cost components over time, it contributes to the projection methodology of cost information from multiple COI studies. The method greatly facilitates economic impact analyses to provide up-to-date information for healthy public policies.