Inhaled corticosteroids are now recommended as first-line therapy for asthma. Although
these drugs clearly improve the symptoms of the disease and the associated physiologic
abnormalities, epidemiologic studies provide important information on their effectiveness in
preventing asthma morbidity and mortality. We review the evidence regarding the role of
inhaled corticosteroids in the prevention of asthma fatality and hospitalization. In the
process, we discuss the methodologic complexities of the nonexperimental studies and the …