Gender Differences in Asthma

Publisher Summary Asthma is a major public health problem. It remains a very common cause of substantial morbidity and occasional mortality. The diagnosis is usually made on the basis of symptom history, clinical exam, and pulmonary function testing. The defining pathology of this chronic disease of the airways is allergic inflammation. The inflammatory response involves abundant eosinophils, as well as multiple other cell types including mast cells, lymphocytes, and neutrophils. However, the precise relationship of the many pathogenic cells and mediators to specific signs or symptoms is complex and remains the subject of active research. There are important gender differences in asthma. A core observation in many epidemiologic studies is that asthma prevalence differs depending on sex and age. In the pre-pubertal population, asthma is more common in boys compared to girls. After puberty, the gender ratio shifts to favor females. The magnitude of this gender difference is perhaps best described as modest (post-pubertal male vs. female odds ratio 0.8, or 44.4d% of males with current asthma were diagnosed at 18 years or older vs. 63.9% for females). However, given the large number of asthmatics (e.g. approximately 10% of the population), these percentage shifts have considerable impact. The basis for these gender effects remains incompletely understood, but significant progress has been made. A clearer understanding of the mechanisms behind this phenomenon will allow for better care of asthmatic patients. This chapter first reviews the clinical and epidemiologic data concerning gender differences in asthma, and then examines the literature regarding potential mechanisms. The potential etiologies examined include developmental differences, estrogens, progesterone, and androgens.