Description

• Chronic, reversible inflammatory airway disease characterized by recurrent attacks of breathlessness and wheezing
• 4 major classifications of asthma severity used primarily to initiate therapy (1,2):
  • Intermittent: Symptoms ≤2 d/wk, nighttime awakenings ≤2×/month, short-acting β-agonist use ≤2 d/wk, no interference with normal activity, and normal forced FEV₁ between exacerbations with FEV₁ (predicted) >80% and FEV₁/FVC >80%
  • Mild persistent: Symptoms >2 d/wk, but not daily, nighttime awakenings 3–4×/month, short-acting β-agonist use >2 d/wk, but not daily, minor limitations in normal activity, and FEV₁ (predicted) >80% and FEV₁/FVC >80%
  • Moderate persistent: Daily symptoms, nighttime awakenings ≥1×/wk but not nightly, daily use of short-acting β-agonist, some limitation in normal activity, and FEV1 (predicted) 60–80% and FEV1/FVC 75–80%
  • Severe persistent: Symptoms throughout the day, nighttime awakenings often 7×/wk, short-acting β-agonist use several times a day, extremely limited normal activity, and FEV₁ (predicted) <60% and FEV₁/FVC <75%

Epidemiology

• Affects 5–10% of population
• One of the most common chronic diseases of childhood, affecting 7 million children
• In children, more common in boys than girls
• In adults, more common in women than men, African Americans than Caucasians

Pregnancy Considerations
In the US, maternal asthma complicates approximately 4–8% of all pregnancies.

Geriatric Considerations
Prevalence of asthma in seniors (>age 65) is 5.3%

Risk Factors

• Host factors: Genetic predisposition, gender, race, BMI
• Environmental: Viral infections, animal and airborne allergens, tobacco smoke, etc.
• Exercise, obesity, and emotional stress
• Aspirin or NSAIDs hypersensitivity or β-blockers
• Food allergies and asthma → increased risk for fatal anaphylaxis from those foods.

• Inheritable component with complex genetics and environment interaction
• A gene-by-environment interaction occurs in which the susceptible host is exposed to environmental factors that are capable of generating IgE, and sensitization occurs.

General Prevention

• Eliminate or modify exposure to asthma triggers (e.g., allergens, smoking, aspirin, NSAIDs)
• Consider allergen immunotherapy.
• Treat comorbidities such as allergic rhinitis.
• Annual influenza vaccine (inactivated influenza vaccine) for age <6 months
• Patients at risk for anaphylaxis should carry an EpiPen.

Pathophysiology

• Airway inflammation begins with inflammatory cell infiltration, sub-basement fibrosis, mucus hypersecretion, epithelial injury, smooth muscle hypertrophy, angiogenesis that then leads to intermittent airflow obstruction and bronchial hyperresponsiveness
• Remodeling of airways may occur (1).

Commonly Associated Conditions

• Atopy: Eczema, allergic conjunctivitis, allergic rhinitis
• Obesity (associated with higher asthma rates)
• Sinusitis
• Gastroesophageal reflux disease (GERD)
• Obstructive sleep apnea (OSA)
• Allergic bronchopulmonary aspergillosis (rare)
• Stress/Depression