| Study characteristics |
| Methods |
Double‐blind parallel group randomised controlled trial |
| Participants |
93 current non smoking adults using only as required beta agonists for asthma. Mean age was 37 years and 70% were female. Mean pre bronchodilator FEV1 was 99.5% ‐ 102.4% of predicted. |
| Interventions |
Budesonide / formoterol 160 μg/4.5 μg as required versus formoterol 4.5 μg as required (delivered doses) |
| Outcomes |
Change in FeNO, asthma symptom scores, asthma free days, morning and evening PEFR, number of inhalations of study drug, FEV1 |
| Notes |
Outcomes reported as baseline and on treatment, combining different time points |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Low risk |
Separate randomisation at each study centre using balanced blocks generated by a computer programme |
| Allocation concealment (selection bias) |
Low risk |
Not specifically described, but likely done |
| Blinding (performance bias and detection bias)
All outcomes |
Low risk |
Double‐blind, identical devices |
| Blinding of participants and personnel (performance bias)
All outcomes |
Low risk |
Double‐blind, identical devices |
| Blinding of outcome assessment (detection bias)
All outcomes |
Low risk |
Double‐blind, identical devices |
| Incomplete outcome data (attrition bias)
All outcomes |
Unclear risk |
Reasons for withdrawal not stated |
| Selective reporting (reporting bias) |
Unclear risk |
No published protocol identified |
