ABSTRACT
The epidemiology of asthma may appear confusing and contradictory to the casual observer. The lack of a gold standard for identifying asthma
and the multitude of factors involved in the pathogenesis contribute to this confusion. Fundamental questions remain about the nature of asthma. Does the recurrent airway obstruction which we call asthma represent a single disease entity or a heterogeneous group of diseases which have a common final pathway? What role does allergy play in asthma? In the 1940s, Rackemann (1947) suggested there were at least two distinct subgroups – extrinsic asthmatics, who tend to start earlier in life (before age 30 years) and have other associated allergic manifestations, and intrinsic asthmatics, who tend to have onset of their disease later in life (after age 40 years) and do not have associated allergic manifestations. Burrows et al. (1989) reported that asthma at all ages is related to allergy. This chapter provides an overview of asthma epidemiology. It is hoped that the reader will look upon this area of research as a challenge and an excellent opportunity where important contributions can be made. There are many questions to be answered and a great deal of solid research that helps to point the way.
