Asthma Diagnosis and Monitoring Guidelines

Diagnosis

• Asthma is diagnosed by combining a compatible clinical history with objective confirmation of variable expiratory airflow limitation; spirometry is essential and must not be omitted. 1, 2
• Variable wheeze, recurrent cough, dyspnea, or chest tightness that is intermittent, worse at night, and provoked by exercise, allergens, or cold air are key clinical indicators. 2, 3
• Symptoms may be perennial, seasonal, continuous, or episodic with diurnal variation; recognizing these patterns aids diagnosis. 2
• A family history of asthma, allergy, or other atopic disorders increases the likelihood of asthma. 2

Objective Diagnostic Testing

• Spirometry for patients ≥ 5 years is the cornerstone of diagnosis and should be performed in all suspected cases. 1, 2
• The Global Initiative for Asthma (GINA) specifies five objective methods to confirm variable airflow limitation:

Special Diagnostic Situations

• In patients already receiving ICS‑containing therapy, repeat objective lung‑function testing after a step‑down of ICS can unmask reversible airflow limitation. 1

Additional Testing

• Chest radiography should be obtained to exclude alternative diagnoses. 2
• Allergy testing is recommended to identify specific triggers and to assess for an allergic/eosinophilic phenotype. 2

Monitoring Framework

• After diagnosis, severity is assessed initially to guide treatment initiation, and control is monitored over time to adjust therapy; severity and control are distinct assessments. 2

Impairment Domain Monitoring (patients ≥ 12 years)

• Parameters include symptom frequency, nighttime awakenings, short‑acting β‑agonist (SABA) use, activity limitation, and lung‑function measurements (FEV₁ or PEF). 2, 1
• Classification of impairment:
  2

Risk Domain Monitoring

• Track exacerbation frequency requiring oral systemic corticosteroids and monitor progressive lung‑function decline with serial spirometry. 2
• All patients, even those with intermittent asthma, can experience severe exacerbations; therefore risk assessment is essential for every individual. 2

Ongoing Monitoring Tools

• Regular spirometry (≥ 5 years) to track lung function over time. 1, 2
• Peak flow monitoring for patients with poor symptom perception. 1
• Standardized symptom questionnaires at each visit. 2
• Medication review focusing on adherence, inhaler technique, and side‑effects. 2

Severe Asthma Considerations

• Approximately 5‑10 % of patients have severe asthma, accounting for about 50 % of asthma‑related healthcare costs; these patients should be referred to asthma specialists. 1
• Phenotyping with biomarkers is advised to determine eligibility for biologic therapies. 1
• More frequent lung‑function testing is recommended to detect progressive decline. 1

Asthma Pathophysiology and Diagnosis

Introduction to Asthma

• Asthma is a chronic inflammatory disorder of the airways characterized by inflammation, bronchial hyperresponsiveness, and airway remodeling, producing variable and reversible airflow obstruction, as stated by the American Thoracic Society 4, 5
• The development of asthma requires both genetic susceptibility and environmental triggers, with 80% of children with two asthmatic parents developing asthma, according to the American Academy of Allergy, Asthma, and Immunology 4, 5

Pathophysiology

• The inflammatory cascade in asthma involves multiple cellular players, including mast cells, eosinophils, T lymphocytes, macrophages, and epithelial cells, which drive the inflammatory response, as noted by the European Respiratory Society 5
• Airflow obstruction in asthma occurs through three distinct mechanisms: bronchoconstriction, airway edema and mucus plugging, and airway remodeling, as described by the American College of Chest Physicians 5

Diagnostic Criteria

• Asthma diagnosis requires a compatible clinical history and objectively confirmed variable expiratory airflow limitation on lung function testing, as recommended by the Global Initiative for Asthma (GINA) 6, 7, 8, 4
• The GINA guidelines recommend five methods to objectively confirm excessive variability in lung function, including positive bronchodilator responsiveness test, excessive PEF variability, improvement after ICS trial, positive bronchial challenge test, and excessive variation between visits, as stated by the European Respiratory Society 6, 7, 9, 8

Pulmonary Function Tests

• The characteristic PFT pattern in asthma is obstructive spirometry with reversible airflow limitation and evidence of bronchial hyperresponsiveness, as noted by the American Thoracic Society 6, 7, 8
• Spirometry findings in asthma include a decreased FEV1, decreased PEF, and reduced FEV1/FVC ratio, indicating airflow obstruction, as described by the European Respiratory Society 10
• Reversibility testing with a positive bronchodilator response demonstrates the hallmark reversibility of asthma, with an FEV1 increase ≥15% AND ≥200 mL, or PEF increase ≥20% AND ≥60 L/min from baseline, as recommended by the American College of Chest Physicians 6, 10

Special Diagnostic Considerations

• For patients already on ICS-containing medications who may not meet standard criteria, the GINA report recommends repeating objective lung function measures and trialing a step-down of ICS treatment, as stated by the Global Initiative for Asthma (GINA) 6, 7
• Additional testing, such as chest x-ray and allergy testing, may be useful in certain cases, as noted by the American Academy of Allergy, Asthma, and Immunology 10, 4

Asthma Diagnosis and Management Independent of Serum IgE Levels

Diagnosis

• Asthma diagnosis requires a compatible clinical history plus objective confirmation of variable expiratory airflow limitation on spirometry (≥12 % and ≥200 mL increase in FEV₁ after bronchodilator or a positive bronchial provocation test), regardless of serum IgE concentration. 11
• The underlying pathophysiology of asthma—chronic airway inflammation, bronchial hyperresponsiveness, and variable airflow obstruction—does not depend on elevated IgE levels. 11

Role of IgE Testing

• Measurement of total or specific IgE is recommended to identify allergen triggers and to define an allergic/eosinophilic phenotype, which can guide allergen immunotherapy or anti‑IgE biologic therapy; normal IgE simply indicates a non‑atopic phenotype and does not exclude asthma. 12, 13

Phenotype and Biologic Considerations

• Elevated IgE may predict a better response to anti‑IgE biologics such as omalizumab, but the majority of type‑2 eosinophilic inflammation in asthma operates independently of IgE levels. 14

Assessment of Severity and Control

• Asthma severity and control are assessed using symptom frequency, exacerbation risk, and lung‑function metrics; serum IgE concentration is not part of these assessments. 11

Non‑asthmatic Eosinophilic Bronchitis (NAEB)

• NAEB presents with chronic cough and sputum eosinophilia that responds to corticosteroids, but it lacks the airway hyperresponsiveness and variable airflow obstruction that define asthma. 15, 13, 16, 14
• NAEB can occur with or without atopy; when atopic markers (elevated IgE) are present it is termed “atopic cough.” 15
• NAEB accounts for roughly 10–30 % of chronic cough cases, shares eosinophilic airway inflammation with asthma, yet mast cells are localized to the epithelium rather than airway smooth muscle. 17, 18, 14

Treatment

• Inhaled corticosteroids (ICS) or combined ICS‑LABA therapy are indicated for all patients with asthma irrespective of IgE status. 13, 14