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For further information, see CMDT Part 9-06: Asthma
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Essentials of Diagnosis
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Respiratory symptoms such as wheezing, dyspnea, or cough, which may be variable in time and severity
Variable limitation on expiratory airflow in pulmonary function testing (PFT) or positive bronchoprovocation challenge
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General Considerations
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A chronic disorder of the airways characterized by
Common aeroallergens
Dust mites
Cockroaches
Cats
Pollen
Nonspecific precipitants
Tobacco increases symptoms and decreases lung function
Certain medications (including aspirin and nonsteroidal anti-inflammatory drugs [NSAID]) may be triggers (Table 9–22)
The pathophysiology of asthma is heterogeneous, but a division into T2-high and T2-low endotypes (marked by high and low levels of classic Th2 cytokines, including IL-4, IL-5, and IL-13) has been shown to be important in the selection of targeted biologic therapies
T2-high asthma phenotypes include allergic asthma, late-onset T2-high asthma, and aspirin/NSAID-associated respiratory disease (AERD)
T2-low asthma phenotypes include nonallergic asthma, which tends to occur in adults and be marked by neutrophilic inflammation and variable response to standard therapies
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Affects 8–10% of the population in the United States
Accounts for 10 million office visits, 1.8 million emergency department visits, and more than 3500 deaths annually in the United States
Slightly more common in boys (< 14 years old) and in women
Hospitalization rates have been highest among Black persons and children
Death rates for asthma are consistently highest among Black persons aged 15–24 years
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Level of asthma control is assessed by frequency of daytime and nighttime symptoms and need for reliever medications (see Table 9–6)
Episodic wheezing, shortness of breath, chest tightness, and cough
Asthma symptoms may occur spontaneously or be precipitated or exacerbated by many different triggers
Excess sputum production
Symptoms are frequently worse at night
Frequency of symptoms is highly variable
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