4. Details of asthma diagnosis and asthma severity in included reviews.

Review	Asthma diagnosis	Asthma severity
Inhaled treatment
Camargo 2003	No information provided	Patients presenting to an ED or its equivalent
Griffiths 2013	Acute exacerbation of asthma	Patients presenting to an ED
Vezina 2014	Acute asthma exacerbation	Hospitalised for an acute asthma exacerbation
Knightly 2017	Acute asthma (excluded chronic or “stable” asthma). “We accepted any reasonable diagnosis of asthma, namely clinical and guideline‐based criteria”	No information provided
Parenteral treatment
Mitra 2005	Acute severe asthma or status asthmaticus	No definition provided for severe Status asthmaticus defined as “acute, severe, refractory exacerbations” Patients were attending ED, hospital wards, or intensive care
Travers 2012a	Severe acute asthma	No definition provided for “severe”. Included patients presenting to an ED (or its equivalent)
Travers 2012b	Severe acute asthma	No definition provided for “severe”. Included patients presenting to an ED or admitted to hospital
Griffiths 2016	Acute asthma	Patients treated in the ED with acute asthma (all severities)
Jat 2012	Acute asthma exacerbation	Not responded to standard therapy with aerosolised beta2‐agonist, with or without aerosolised anticholinergic drugs and oral or parenteral corticosteroid, for at least 1 hour
Other interventions to reduce the work of breathing
Rodrigo 2006	Clinical diagnosis asthma exacerbation (according to accepted criteria such as those published by the American Thoracic Society). Excluded patients with COPD	Presenting to an ED or equivalent care setting. Excluded patients requiring mechanical ventilation at presentation
Korang 2016	Asthma attack (as defined by the trialists). Excluded children with pneumonia, aspiration, bronchiolitis, cystic fibrosis, or any ciliary dyskinetic syndrome	Children hospitalised for an asthma attack
Other interventions
Normansell 2018	Asthma exacerbation. Excluded pneumonia, COPD, and bronchiectasis	Presented to the ED, primary care, outpatient clinics, or inpatient wards. Included both inpatients and outpatients
Watts 2012	Acute asthma	Presenting for acute medical care to an ED or equivalent setting

COPD: chronic obstructive pulmonary disease; ED: emergency department.