ABSTRACT
There is no illness more in need of epidemiological study than asthma. Despite significant
advances in our understanding of the pathophysiology, course, and management of this
disease, its prevalence, morbidity, and mortality appear to be on the rise, and the
reasons are not entirely clear. Historically, epidemiological studies of asthma have
suffered from the lack of a standardized definition of the disease and the lack of
a ``gold standard'' with which to compare objective measures for diagnosing the illness.
Recent studies have overcome some of these difficulties to provide solid epidemiological
data on asthma from a global perspective. International studies have demonstrated
that asthma prevalence varies significantly worldwide, with Western, English-speaking
countries having the highest prevalence rates. In the United States, the prevalence
of asthma has increased by nearly 75% in the past 2 decades. Young children, blacks,
and Hispanics tend to be disproportionately affected by the disease. Asthma morbidity,
as measured by emergency department visits, hospitalizations, and medication usage
has been increasing worldwide, and asthma mortality, although still rare, has been
increasing as well. Epidemiological studies have provided important information regarding
the etiology and risk factors for asthma. The disease is emerging as a prototypical
illness for the alliance of genetic and environmental disease determinants. Some of
the most important conclusions relate to the developing immune system and the timing
of certain allergic or infectious exposures that may predispose the child to develop
asthma. Indeed, advances in epidemiological study will be critical if we are to intervene
and reverse some of asthma's disturbing trends.
KEYWORDS
Asthma - hyperresponsiveness - genetic - environmental - morbidity
