What are the guidelines to diagnose and treat asthma?

Asthma Diagnosis Guidelines

Asthma diagnosis requires both characteristic symptoms (recurrent wheezing, breathlessness, chest tightness, or cough) AND objective demonstration of reversible airflow obstruction using spirometry in all patients ≥5 years old. 1, 2

Diagnostic Criteria

Clinical History Requirements

• Document episodic respiratory symptoms: wheezing, breathlessness, chest tightness, and cough (particularly at night or early morning) 1, 2
• Assess symptom frequency: daytime symptoms, nighttime awakenings, and frequency of short-acting β-agonist use 1
• Identify trigger exposures: allergens, irritants, exercise, viral infections, weather changes, and medications 1, 2
• Evaluate activity limitations: interference with school/work attendance and physical activities 1
• Obtain family history: parental asthma, atopic dermatitis, or allergic conditions 3

Objective Testing - Spirometry (Mandatory)

• Perform spirometry at initial assessment in all patients ≥5 years old before initiating treatment 3, 1
• Demonstrate reversible airflow obstruction: FEV₁ improvement ≥12% AND ≥200 mL after short-acting bronchodilator administration 1, 2
• Measure FEV₁/FVC ratio: This is more sensitive than FEV₁ alone in children for detecting obstruction 3, 2
• Normal FEV₁/FVC thresholds by age: 85% (ages 8-19), 80% (ages 20-39), 75% (ages 40-59), 70% (ages 60-80) 3

Additional Testing When Spirometry is Normal

When spirometry shows no obstruction but clinical suspicion remains:

• Bronchoprovocation testing (methacholine, histamine, or exercise challenge) - a negative test helps rule out asthma 1
• Peak expiratory flow monitoring over 2-4 weeks to document variability 1
• Fractional exhaled nitric oxide (FeNO) measurement to assess eosinophilic inflammation 3, 1

Critical Differential Diagnoses to Exclude

In adults:

• COPD (smoking history, progressive symptoms, less reversibility) 1
• Congestive heart failure (orthopnea, edema, elevated BNP) 1
• Vocal cord dysfunction (inspiratory flow-volume loop flattening on spirometry) 1
• Pulmonary embolism (acute onset, risk factors) 1
• ACE inhibitor-induced cough (medication history) 1

In children:

• Foreign body aspiration (sudden onset, unilateral findings) 1
• Cystic fibrosis (chronic productive cough, failure to thrive) 1
• Vascular rings (stridor, dysphagia) 1
• Recurrent aspiration (feeding difficulties) 1

Severity Classification (Before Treatment Initiation)

Classify severity using both impairment and risk domains to guide initial therapy. 3, 1, 2

Intermittent Asthma

• Symptoms ≤2 days/week 3, 1
• Nighttime awakenings ≤2 times/month 3, 1
• SABA use ≤2 days/week 3, 1
• No interference with normal activities 3, 1
• FEV₁ >80% predicted with normal FEV₁/FVC 3, 1
• 0-1 exacerbations requiring oral corticosteroids per year 3, 1

Mild Persistent Asthma

• Symptoms >2 days/week but not daily 3, 1
• Nighttime awakenings 3-4 times/month 3, 1
• SABA use >2 days/week but not daily 3
• Minor activity limitation 3
• FEV₁ ≥80% predicted 3

Moderate Persistent Asthma

• Daily symptoms 3, 1
• Nighttime awakenings >1 time/week but not nightly 3, 1
• Daily SABA use 3, 1
• Some activity limitation 3, 1
• FEV₁ 60-80% predicted 3, 1

Severe Persistent Asthma

• Symptoms throughout the day 3, 1
• Nighttime awakenings often 7 times/week 3, 1
• SABA use several times per day 3, 1
• Extremely limited activities 3, 1
• FEV₁ <60% predicted 3, 1

Risk assessment: ≥2 exacerbations requiring oral corticosteroids in the past year indicates higher risk regardless of impairment level. 3, 1

Common Diagnostic Pitfalls

• Never diagnose asthma without objective testing (spirometry or documented peak flow variability) in patients ≥5 years old 1, 2
• Difficulty diagnosing patients already on inhaled corticosteroids: Consider stopping treatment (if safe) to demonstrate reversibility, or use bronchoprovocation testing 4
• Variable presentation: Patients may have normal lung function and examination between episodes 3, 5
• Pediatric challenges: Classic symptoms may not be present in young children; consider asthma risk profile (parental asthma, atopic dermatitis, food sensitization, eosinophilia) 3
• Comorbidities obscuring diagnosis: Rhinitis, sinusitis, GERD, obesity, and obstructive sleep apnea can complicate the clinical picture 1, 6

Monitoring After Diagnosis

• Repeat spirometry: At initial assessment, after treatment initiation when symptoms stabilize, during periods of progressive loss of control, and at least every 1-2 years 3, 1, 6
• Follow-up visit schedule: Every 2-6 weeks when initiating therapy or stepping up treatment; every 1-6 months once control is achieved; every 3 months when considering step-down 3, 1, 6
• Assess at each visit: Asthma control level, inhaler technique, written action plan adherence, environmental triggers, and comorbidities 6, 2