Understanding the economic burden of asthma.

The economic impact of asthma is large and growing, and the use of economic outcomes is increasing. Such outcomes serve as the basis for studies of the efficiency of care and are being reported increasingly as outcomes of clinical trials. This article presents the basic components of a cost-of-illness study, the in-fluences that have an impact on these components, the relation of economic indicators to clinical outcomes, and the relative importance of the economic factors for differing groups in society.