Cost of illness: A critical review of estimation methodologies

Studies on the cost of illness arise to advance knowledge and estimation of the economic burden of disease. These identify, quantify and value all the economic resources linked to a disease, and classify them as direct, indirect and intangible costs. The aim of this paper is to critically describe the different methods for estimating each of these costs. The valuation of the costs of an illness involves a vector of prices and quantities. The quantities arise from the resources used or lost. Prices are estimated from the market value of the good or service or, if it is a non-market good or service, then prices are estimated from proxy variables or specific methods of estimation of individual preferences. The main methodological and theoretical weaknesses found deal with the estimation of the ‘time’ resource, the presence of externalities and market imperfections and the violation of some assumptions of economic theory.