What is Asthma?
Asthma is a chronic heterogeneous airway disease characterised by airway hyperresponsiveness, reversible airflow obstruction, and airway inflammation. It is defined clinically by variable respiratory symptoms (wheeze, breathlessness, chest tightness, cough) with variable expiratory airflow limitation. GINA 2024 and NICE 2021 now stratify asthma by phenotype (allergic/eosinophilic, non-allergic/neutrophilic, late-onset eosinophilic, obesity-related) to guide biological therapy.
Pathophysiology
Allergic (T2-high) asthma: IgE-mediated sensitisation to allergens triggers mast cell degranulation and eosinophilic inflammation driven by IL-4, IL-5, IL-13. Non-allergic asthma: neutrophilic or paucigranulocytic inflammation driven by innate immune pathways. Both lead to airway smooth muscle hypertrophy, mucus hypersecretion, subepithelial fibrosis, and bronchoconstriction. SABA overuse masks poor control and increases asthma death risk (Asthma Death Inquiry data).
Clinical Features & Symptoms
- Recurrent episodes of wheeze
- Dyspnoea on exertion or at rest
- Chest tightness
- Cough (especially nocturnal or early morning)
- Symptoms vary over time and in intensity
- Triggered by allergens, exercise, cold air, NSAIDs, viral infections
- Symptoms responsive to bronchodilators and ICS
Diagnosis
NICE 2021 diagnostic pathway: FeNO testing (≥40 ppb highly specific for eosinophilic asthma) + spirometry (FEV₁/FVC <70%, reversibility ≥12% + 200 mL with bronchodilator). Variable PEF: diurnal variation >10% on ≥3 days/week. Bronchial challenge (methacholine/mannitol) if spirometry normal. Blood eosinophils ≥300 cells/µL supports T2-high phenotype.
Current Treatment Guidelines
SABA-free approach (GINA 2024 / NICE 2021)
Class I, Level AGINA 2024 recommends as-needed low-dose ICS-formoterol as preferred reliever (not SABA-only) for all adults from Step 1. Reduces exacerbations vs SABA-only PRN. NICE 2021: do not prescribe SABA alone as first-line.
MART (Step 3): Maintenance and Reliever Therapy
Class I, Level AICS-formoterol single inhaler for both maintenance and reliever in uncontrolled asthma on low-dose ICS. Reduces severe exacerbations by 30–50% vs fixed-dose ICS + SABA. Budesonide/formoterol preferred (most evidence).
Step up: Add LAMA (Step 4)
Class I, Level AAdd tiotropium respimat to ICS-LABA in adults with uncontrolled asthma. Reduces exacerbations and improves lung function.
Biologics for severe asthma (Step 5)
Class I, Level AOmalizumab (anti-IgE) for allergic asthma. Mepolizumab, benralizumab, dupilumab (anti-IL-4/13) for severe eosinophilic asthma. Tezepelumab (anti-TSLP) for mixed phenotype. FeNO and blood eosinophils guide biologic choice.
Written asthma action plan
Class I, Level AProvide all patients with a personalised written asthma action plan. Reduces asthma hospitalisations by 30–40%. Include triggers, peak flow zones, and when to escalate care.
Monitoring & Treatment Targets
ACQ (Asthma Control Questionnaire) or ACT score at each visit. Peak flow monitoring. Annual spirometry. FeNO if considering step-down. Inhaler technique check at every visit. Review SABA use >3 canisters/year — indicator of poor control.
Key Clinical Trials
Clinical Guidelines
External Resources
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Frequently Asked Questions
What is MART therapy in asthma?
MART (Maintenance and Reliever Therapy) uses a single inhaler containing ICS-formoterol for both regular maintenance dosing AND as-needed relief. As formoterol is a fast-acting LABA, it provides immediate bronchodilation when used as a reliever while simultaneously delivering an anti-inflammatory ICS dose. NICE 2021 recommends MART at Step 3 for adults uncontrolled on low-dose ICS alone. Budesonide/formoterol has the most evidence.
Should I prescribe a SABA inhaler for mild asthma?
GINA 2024 and NICE 2021 both advise against SABA-only prescribing for mild asthma. SABA overuse is associated with increased asthma deaths, worsening airway inflammation, and reduced bronchodilator response. The preferred approach at Step 1-2 is as-needed low-dose ICS-formoterol (e.g. budesonide/formoterol 200/6 micrograms as needed), which reduces exacerbation risk compared to SABA-only.
Medical disclaimer: This content is intended for qualified healthcare professionals and does not constitute medical advice. Always apply clinical judgment and refer to current local guidelines and institutional protocols.