Epidemiology of asthma: prevalence and burden of disease.

While clinical guidelines clearly define mechanisms for asthma diagnosis based upon history, lung function testing, symptoms, and physical examination, surveillance for asthma is much less straightforward. Epidemiologists have long debated the best means of assessing the scope and burden of asthma, seeking to reduce the potential for confounding introduced by differential means of diagnosis and even slight differences in surveillance questions, both of which can bias surveillance results such that we over- or undercount cases. This chapter will provide an overview of asthma epidemiology in the USA and internationally, as well as review of the data and findings from the major surveillance systems, a discussion of a networked approach to the science and evaluation of therapeutic treatments using the exemplar of the Inner-City Asthma Network, and assessment of public health implications.