| Asthma is a common lung disease, caused by airway reaction to various
stimuli. It is a chronic condition, marked by acute exacerbations and may
be life threatening if not properly managed. Approximately
10–12% of adults and 15% of children suffer from asthma; it affects men and women equally.
In developing countries where the prevalence of
asthma had been much lower, there is a rising incidence that appears to
be associated with increased urbanization. Each
year, approximately 1.9 million emergency room visits, 470,000 hospital
admissions and 5000 deaths in the United States are attributed to asthma.
Prevalence, hospitalizations and fatal asthma exacerbations have all increased
in the United States over the past 20 years. Most
patients with asthma in affluent countries are atopic, with allergic
sensitization to the house dust mite Dermatophagoides pteronyssinus
and other environmental allergens.
Asthma triggers are varied, and include inhaled allergens, exercise, upper
respiratory tract infections, GERD, cold and stress. Features of asthma
may include breathlessness, cough, wheezing, and chest tightness. Symptoms
are frequently worse at night or in the early morning. Pulmonary function
testing is typically abnormal and shows limitation of airflow with reversibility
after bronchodilator therapy.
The National Asthma Education and Prevention Program (NAEPP) has developed an asthma classification scheme which
may help direct conventional asthma therapy, as well as identify patients at
high risk of developing life threatening exacerbations.
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