What are the diagnostic criteria and treatment options for asthma?

Diagnosis of Asthma

Asthma diagnosis requires a compatible clinical history of episodic respiratory symptoms AND objective confirmation of variable expiratory airflow limitation through pulmonary function testing. 1

Diagnostic Criteria

Clinical History Assessment

• Key symptoms to identify:

  • Recurrent episodes of wheezing
  • Cough (particularly worse at night)
  • Recurrent difficulty breathing
  • Recurrent chest tightness 2

• Symptom patterns suggestive of asthma:

  • Symptoms worsen with:
    • Exercise
    • Viral infections
    • Exposure to allergens (animals, dust mites, mold, pollen)
    • Irritants (smoke, chemicals)
    • Weather changes
    • Strong emotions
    • Stress 2
  • Symptoms occur or worsen at night, awakening the patient 2

Objective Testing (Required for Diagnosis)

1. Spirometry with bronchodilator reversibility testing (gold standard):

   • Demonstrates airflow obstruction: FEV₁/FVC ratio below lower limit of normal
   • Positive bronchodilator response: increase in FEV₁ of ≥12% and ≥200 mL from baseline after bronchodilator administration 2, 1

2. Alternative objective testing methods (when spirometry is normal but clinical suspicion remains):

   • Peak Expiratory Flow (PEF) monitoring: Excessive variability in twice-daily measurements over 2 weeks (diurnal variation >20%) 2, 1
   • Bronchial challenge testing: Assesses airway hyperresponsiveness 1, 3
   • Response to treatment: Increase in lung function after 4 weeks of inhaled corticosteroid treatment 2
   • Fractional exhaled nitric oxide (FeNO): Values ≥45-50 ppb suggest eosinophilic inflammation (particularly useful in atopic asthma) 1

Diagnostic Pitfalls to Avoid

1. Relying solely on clinical symptoms without objective testing:

   • Spirometric criteria alone is inadequate - only 54.7% of patients meeting ATS bronchodilator response criteria actually had clinical asthma in one study 4
   • Diagnosis must combine symptoms AND objective evidence of variable airflow limitation 5

2. Testing during asymptomatic periods:

   • May yield false negative results
   • Repeated testing may be necessary 1

3. Misinterpreting normal spirometry:

   • Normal spirometry is common in mild asthma when patients are not symptomatic
   • Consider bronchial challenge testing when spirometry is normal but clinical suspicion remains 6, 3

4. Confusing asthma with other conditions:

   • Vocal cord dysfunction can mimic asthma symptoms but typically doesn't respond to asthma medications 2
   • COPD in adult smokers may present similarly - diffusing capacity testing can help differentiate 6

Treatment Approach After Diagnosis

1. Initial therapy based on severity:

   • Intermittent asthma: Short-acting beta-agonists (SABAs) as needed
   • Persistent asthma: Daily inhaled corticosteroids (ICS) as controller medication 2, 1

2. Step-up therapy for inadequate control:

   • Combination therapy with ICS + long-acting beta-agonist (LABA) like fluticasone/salmeterol 7
   • Dosing: 1 inhalation twice daily, with strength based on asthma severity 7

3. Regular monitoring and follow-up:

   • Assess symptom control and lung function regularly
   • Adjust therapy based on control assessment
   • Follow-up visits at 1-6 month intervals after control is achieved 1
   • Spirometry recommended at least every 1-2 years 1

Special Considerations

• Children ages 0-4 years: Diagnosis is challenging due to difficulty obtaining objective lung function measurements. Balance the risk of inappropriate prolonged therapy against the risk of underdiagnosis 2

• Asthma-COPD overlap: Consider when patients show features of both conditions. Diagnosis requires three or more features of each disease 2

• Referral to specialist: Consider when symptoms are atypical, differential diagnosis is unclear, or additional testing is indicated 2

Remember that asthma is a heterogeneous disease with both atopic and non-atopic phenotypes, requiring a comprehensive diagnostic approach that combines clinical assessment with objective testing to confirm variable airflow limitation.