# Diagnosis and Assessment of Asthma — GINA 2024

## Definition of Asthma

Asthma is a heterogeneous disease, usually characterized by chronic airway inflammation. It is defined by a history of respiratory symptoms such as wheeze, shortness of breath, chest tightness, and cough that vary over time and in intensity, together with variable expiratory airflow limitation.

## Diagnostic Criteria

Diagnosis of asthma requires both:
1. **History of variable respiratory symptoms** — wheeze, shortness of breath, chest tightness, and/or cough; symptoms vary over time and in intensity; symptoms often worse at night or on waking; symptoms often triggered by exercise, allergens, cold air, laughter, or irritants; symptoms often appear or worsen with viral infections
2. **Confirmed variable expiratory airflow limitation** — documented excessive variability in lung function (one or more of the tests below), AND documented airflow limitation

## Objective Tests for Variable Airflow Limitation

### Spirometry with Bronchodilator Reversibility (Preferred)

- **Positive bronchodilator reversibility (BDR) in adults:** Increase in FEV1 >12% AND >200 mL from baseline, 10-15 minutes after 200-400 mcg salbutamol (albuterol) or equivalent
- A positive BDR is more likely if bronchodilator medication is withheld before testing: SABA >=4 hours, LABA >=15 hours
- If spirometry is normal, repeat when the patient is symptomatic, or after withholding bronchodilators

### Peak Expiratory Flow (PEF) Variability

- **Average daily diurnal PEF variability >10% in adults** supports the diagnosis
- Calculated as: (day's highest PEF - day's lowest PEF) / mean of day's highest and lowest PEF x 100, averaged over 1-2 weeks
- Record PEF twice daily (morning and evening), using the best of 3 readings each time

### Additional Diagnostic Tests

- **Excessive variability in PEF between visits:** >20% variability in PEF between visits
- **Positive exercise challenge test:** Fall in FEV1 >10% AND >200 mL from baseline
- **Positive bronchial provocation test:** Fall in FEV1 >=20% with standard dose methacholine or histamine, OR >=15% with standardized hyperventilation, hypertonic saline, or mannitol challenge
- **Excessive variability in lung function between visits:** Variation in FEV1 >12% AND >200 mL between visits, outside of respiratory infections

## Assessment of Asthma Symptom Control

Assess symptom control over the previous 4 weeks using these four criteria:

| Criterion | Well Controlled | Partly Controlled | Uncontrolled |
| :--- | :--- | :--- | :--- |
| **Daytime symptoms more than twice/week** | None of these | 1-2 of these | 3-4 of these |
| **Any night waking due to asthma** | | | |
| **Reliever needed more than twice/week** (not including pre-exercise use) | | | |
| **Any activity limitation due to asthma** | | | |

- **Well controlled:** None of the above criteria present
- **Partly controlled:** 1-2 of the above criteria present
- **Uncontrolled:** 3-4 of the above criteria present

## Assessment of Future Risk

In addition to symptom control, assess risk factors for:
- **Exacerbations:** History of intubation/ICU admission for asthma, >=1 severe exacerbation in the past 12 months, overuse of SABA (>1 canister/month or >=3 canisters/year), inadequate ICS use (not prescribed, poor adherence, incorrect inhaler technique), low FEV1 (especially <60% predicted), major psychological or socioeconomic problems, exposures (smoking, allergens), comorbidities (obesity, rhinosinusitis, food allergy), sputum or blood eosinophilia, pregnancy
- **Fixed airflow limitation:** Lack of ICS treatment, exposure to tobacco smoke or noxious chemicals, low initial FEV1, chronic mucus hypersecretion, sputum or blood eosinophilia
- **Medication side effects:** Frequent oral corticosteroid courses, high-dose or potent ICS, concurrent use of P450 inhibitors

## ICS Dose Categories for Adults and Adolescents (>=12 years)

| ICS Drug | Low Dose (mcg/day) | Medium Dose (mcg/day) | High Dose (mcg/day) |
| :--- | :--- | :--- | :--- |
| **Beclomethasone dipropionate (pMDI, standard particle)** | 200-500 | >500-1000 | >1000 |
| **Beclomethasone dipropionate (pMDI, extrafine particle)** | 100-200 | >200-400 | >400 |
| **Budesonide (DPI)** | 200-400 | >400-800 | >800 |
| **Ciclesonide (pMDI, extrafine particle)** | 80-160 | >160-320 | >320 |
| **Fluticasone furoate (DPI)** | 100 | — | 200 |
| **Fluticasone propionate (DPI)** | 100-250 | >250-500 | >500 |
| **Fluticasone propionate (pMDI, standard particle)** | 100-250 | >250-500 | >500 |
| **Mometasone furoate (DPI)** | 200 | 400 | >=800 |
| **Mometasone furoate (pMDI, standard particle)** | 200-400 | >400 | — |

## Limitations

- Spirometry may be normal between exacerbations, especially in mild or intermittent asthma; repeated testing may be necessary.
- A positive bronchodilator response can also be seen in COPD and asthma-COPD overlap.
- Peak flow variability may be effort-dependent and requires patient compliance for home monitoring.
- The diagnostic criteria apply to adults and adolescents >=12 years; different thresholds exist for children aged 6-11 years.
- In patients already on controller treatment, diagnosis may require step-down or repeat testing to confirm variability.
