asthma
Contents
Chronic airway inflammation with variable expiratory airflow limitation. Diagnosis requires both typical symptoms (wheeze, cough, dyspnoea, chest tightness) and objective evidence of variability. SABA-only treatment is no longer recommended at any step — ICS-formoterol as needed is the foundation of modern management (GINA 2024).
diagnosis
Two criteria — both required:
- Variable respiratory symptoms — wheeze, dyspnoea, chest tightness, cough; worse at night or early morning; triggered by exercise, allergens, cold air, viral infections; vary over time and in intensity
- Variable expiratory airflow limitation — documented by at least one of:
| Test | Positive result |
|---|---|
| BD response on spirometry | FEV1 increase ≥ 12% and ≥ 200 mL from baseline (GINA 2024); ERS/ATS 2022 proposed > 10% of predicted — not yet adopted by GINA (ERS/ATS 2022) |
| PEF variability | > 10% diurnal variation (amplitude % mean, twice-daily readings over 1–2 weeks) |
| Methacholine challenge | PC20 < 4 mg/mL (high sensitivity; less specific) |
| Exercise challenge | FEV1 fall > 10% and > 200 mL from baseline |
| Between-visit FEV1 variation | > 12% and > 200 mL change between visits |
Once ICS is started, demonstrating variability becomes harder. If a patient is already on ICS and diagnosis is uncertain, consider step-down challenge (under supervision) or methacholine challenge while on treatment — a positive result confirms hyperresponsiveness but a negative result on ICS does not exclude asthma.
A normal FEV1/FVC does not rule out asthma. Conversely, a low FEV1/FVC with BD response may also occur in COPD. The diagnosis is clinical + physiological — never one test in isolation.
assessing control
Assess over the previous 4 weeks (GINA 2024):
| Level of control | Symptoms (past 4 weeks) |
|---|---|
| Well controlled | None of the domains below |
| Partly controlled | 1–2 of the domains below |
| Uncontrolled | 3–4 of the domains below |
Symptom domains:
- Daytime symptoms > 2×/week?
- Any night waking due to asthma?
- Reliever needed for symptoms > 2×/week?
- Any activity limitation due to asthma?
CTS approach — 3 questions at each encounter (CTS 2021)
- Is asthma controlled by CTS criteria (see above)?
- Is the patient at higher risk of exacerbation?
- Is inhaler technique correct? Are comorbidities addressed?
Higher risk of exacerbation (any one of):
- Any previous severe exacerbation (OCS, ED visit, or hospitalisation)
- Poorly controlled asthma per CTS criteria
- SABA overuse (> 2 canisters/year)
- Current smoker
In addition to symptom control, assess future risk (GINA 2024):
- Exacerbations in past 12 months (any requiring OCS = high risk)
- FEV1 < 80% predicted (or declining)
- Poor adherence or incorrect inhaler technique
- Ongoing allergen exposure, smoking, obesity, GERD, rhinosinusitis
- Blood eosinophils ≥ 0.3 × 10⁹/L, elevated FeNO
risk factors for severe/fatal asthma
- Prior near-fatal exacerbation (intubation/ICU)
- ≥ 2 hospitalisations or ≥ 3 ED visits in past year
- Currently using or recently stopped OCS
- Not currently using ICS / poor adherence
- Over-use of SABA (> 1 canister/month)
- Comorbid psychiatric disease, food allergy
- Illicit drug use
treatment — GINA track 1 (preferred)
ICS-formoterol as reliever at every step. No SABA-only treatment.
| Step | Maintenance | Reliever | Typical patient |
|---|---|---|---|
| 1 | None | PRN low-dose ICS-formoterol | Symptoms < 2×/month |
| 2 | None | PRN low-dose ICS-formoterol | Symptoms ≥ 2×/month but < daily |
| 3 | Low-dose ICS-formoterol maintenance | PRN ICS-formoterol (MART) | Most days or waking ≥ 1×/week |
| 4 | Medium-dose ICS-formoterol maintenance | PRN ICS-formoterol (MART) | Uncontrolled on step 3 |
| 5 | High-dose ICS-formoterol + add-on (LAMA, biologic) | PRN ICS-formoterol | Refer for phenotyping → severe asthma |
SMART/MART therapy
Single-inhaler maintenance and reliever therapy — budesonide-formoterol (or BDP-formoterol) used for both daily maintenance and as-needed relief. Formoterol’s rapid onset allows it to function as a reliever; the ICS component treats the inflammation driving each episode of symptoms.
Evidence base:
- SYGMA 1 (2018) — PRN budesonide-formoterol superior to PRN SABA for symptom control in mild asthma
- SYGMA 2 (2018) — PRN budesonide-formoterol non-inferior to daily ICS for exacerbation prevention, with 75% less ICS exposure
- NOVEL START (2019) — open-label confirmation; PRN budesonide-formoterol reduced exacerbations by 51% vs PRN SABA
SABA treats bronchospasm but not the underlying inflammation. Each exacerbation treated with SABA alone permits eosinophilic airway inflammation to persist. PRN ICS-formoterol delivers anti-inflammatory treatment at the moment of symptoms — matching treatment to disease activity. SABA overuse (≥ 3 canisters/year) is independently associated with increased exacerbation risk.
treatment — GINA track 2 (alternative)
SABA as reliever with a separate ICS controller. Used when ICS-formoterol is unavailable or unaffordable.
| Step | Maintenance | Reliever |
|---|---|---|
| 1 | Low-dose ICS taken with each SABA use | PRN SABA |
| 2 | Daily low-dose ICS | PRN SABA |
| 3 | Low-dose ICS-LABA | PRN SABA |
| 4 | Medium/high-dose ICS-LABA | PRN SABA |
| 5 | Refer — add LAMA, biologic, low-dose OCS | PRN SABA |
ICS-SABA combination rescue
MANDALA (2022) — in moderate-to-severe asthma, PRN fixed-dose albuterol-budesonide reduced severe exacerbations by 26% vs albuterol alone (HR 0.74), with lower total corticosteroid exposure (84 vs 130 mg prednisone equivalents/year). This led to regulatory approval of albuterol-budesonide (AirSupra) as the first ICS-SABA combination rescue inhaler.
BATURA (2025) — in mild asthma, as-needed albuterol-budesonide reduced severe exacerbations by 47–53% vs albuterol alone, extending the ICS-SABA rescue concept to the mild asthma population.
Advise patients using separate inhalers to take their ICS and SABA together during symptom episodes — this simulates the combined inhaler effect and ensures every rescue dose delivers anti-inflammatory treatment alongside bronchodilation (GINA 2024).
CTS vs GINA — key differences
| Issue | CTS 2021 | GINA 2024 |
|---|---|---|
| Preferred reliever | SABA (with ICS controller) | ICS-formoterol at all steps |
| PRN SABA alone | Acceptable if well-controlled, low risk | Recommends against in all patients |
| Mild asthma backbone | Daily low-dose ICS + PRN SABA | PRN ICS-formoterol (no daily controller) |
| Classification | Retrospective — based on therapy needed to achieve control | Based on current symptom burden and lung function |
Many Canadian respirologists use a hybrid approach — GINA track 1 (MART) where budesonide-formoterol is available, with CTS criteria for defining control and risk.
ICS dosing — adults
| Low dose | Medium dose | High dose | |
|---|---|---|---|
| Budesonide (DPI) | 200–400 µg/day | 400–800 µg/day | > 800 µg/day |
| Fluticasone propionate (DPI) | 100–250 µg/day | 250–500 µg/day | > 500 µg/day |
| Ciclesonide (MDI) | 80–160 µg/day | 160–320 µg/day | > 320 µg/day |
| Beclomethasone (MDI, HFA) | 200–500 µg/day | 500–1000 µg/day | > 1000 µg/day |
add-on therapies
| Therapy | When | Notes |
|---|---|---|
| LAMA (tiotropium) | Step 4–5, add to ICS-LABA | Modest benefit on exacerbations and FEV1 |
| LTRA (montelukast) | Alternative to step-up at step 2–3 | Less effective than ICS; shared decision given neuropsychiatric AEs (GINA 2024 caution) |
| Azithromycin (low-dose) | Refractory non-eosinophilic asthma | 250 mg 3×/week; reduces exacerbations regardless of phenotype; ECG and LFTs at baseline |
| Biologics | Step 5 — see severe asthma | Phenotype-directed; requires referral and biomarker assessment |
| Low-dose OCS | Last resort, step 5 only | Minimise dose and duration; always consider biologic first |
stepping down
- Review every 2–3 months once controlled; step down when stable for ≥ 2–3 months
- Never stop ICS completely — even in well-controlled patients, step down to PRN ICS-formoterol rather than stopping
- Reduce ICS dose by ~25–50% at each step-down
- Seasonal variation: may need temporary step-up during high-risk periods (viral season, allergen exposure)
when to refer
- Uncontrolled on medium-dose MART (step 4) despite confirmed adherence and technique
- Diagnostic uncertainty — consider asthma mimics
- ≥ 2 exacerbations/year requiring OCS despite step 3–4 therapy
- Need for continuous or frequent OCS
- Suspected occupational asthma — see occupational asthma
- Suspected severe asthma requiring biologic assessment — see severe asthma
- Life-threatening exacerbation at any time
what NOT to do
- SABA-only treatment at any step — outdated and harmful
- LABA monotherapy (without ICS) — associated with increased asthma mortality; always pair with ICS
- Use FEV1/FVC < 0.70 as the sole criterion (that’s for COPD; asthma uses LLN and variability)
- Diagnose asthma without documenting objective airflow limitation
- Prescribe montelukast as first-line without discussing neuropsychiatric risks
- Escalate therapy without checking adherence, inhaler technique, and comorbidities first
- Delay biologic referral while cycling through repeated OCS courses