Svedmyr 1999.

Methods	Design: 12 months (or maximum of 6 treatments), randomised, parallel‐group, double blind placebo‐controlled trial. Pre‐emptive study. Setting: Multicentre, (Recruited from 4 paediatric departments in Sweden) Date of study: Not reported
Participants	Participants: n = 55 (28 received budesonide: 27 received placebo) Baseline characteristics: mean age (intermittent ICS: 2.08 years, placebo 2.17 years; range 1‐3.92 years); gender ‐ male (intermittent ICS 60.7% to placebo 77.8%). Diagnostic criteria: Doctor's diagnosis of wheezy bronchitis or asthma. Asthma severity: N/A Inclusion criteria: Children aged 1‐3 years, at least three episodes of wheezing during URTI and asthma symptoms during the last two airway infections; asthma symptoms lasted for at least 3 days during the URTI. Exclusion criteria: If the first symptom did not develop into an URTI within 24 hours, the study period was withheld.
Interventions	Run‐in period: not stated. Interventions: 1. treatment started at the first sign of an URTI and lasted for 10 d. The dosage regimen was a nominal dose of budesonide 400 µg q.i.d. for the first 3 d and budesonide 400 µg b.i.d. for the following 7 d. 2. Placebo equivalent. Concomitant medication Treatment with additional beta2‐agonists via the spacer and/or theophylline was allowed when needed. When cromoglycate was used, the dose was fixed and a separate spacer was used.
Outcomes	Primary outcome(s): asthma symptom scored by parents twice daily on a 4‐graded scale (0–3). Secondary outcome(s): 1. sleep disturbance; 2. use of rescue medication (oral corticosteroids); 3. need for medical care; 4. adverse events.
Notes	Funding: Unknown
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomised
Allocation concealment (selection bias)	Unclear risk	Inadequate details were reported.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Double‐blind.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No high attrition rate. Reasons for withdrawal were reported. The primary outcome was clearly specified.
Selective reporting (reporting bias)	Low risk	No apparent bias was noted.
Other bias	Low risk	No apparent bias was noted.

AUC = area under the curve.

EFD = proportion of episode free days.

FEV1 = forced expiratory volume in one second.

ICS = inhaled corticosteroids.

LTRA = leukotriene receptor antagonists.

RTI = respiratory tract infection.