Weir 1990a.

Methods	Design: crossover, 2 weeks washout Randomisation: yes, method not stated Blinding: double blind, double dummy Withdrawals: stated
Participants	Setting: single centre study, hospital outpatient clinic Number eligible: not stated Number enrolled: 127 Number in treatment group: 127 Number in control group: 127 Number of withdrawals (treatment/control): 20 withdrawals Number completing trial (treatment/control): 107 (crossover) Age range: mean 62.9 yr (SD 9.0) Sex: 82M, 25F Ethnicity: not stated COPD diagnosis: adult onset chronic airflow obstruction of at least 5 yr duration and FEV1<70% predicted Severity of COPD: mean FEV1 44.2% predicted Inclusion criteria: as above, 95/107 were current or ex‐smokers Exclusion criteria: asthma, respiratory symptoms in childhood, variability in symptoms except in association with infections, acute attacks of wheezing and breathlessness, deterioration after exposure to specific allergens, use of oral or inhaled steroids in previous 6 month Baseline characteristics of treatment/control groups: crossover
Interventions	BDP 500 µg, 3 times a day (1500 µg/d) Placebo 3 times a day metered‐dose inhaler 2 weeks each treatment period (crossover)
Outcomes	Spirometry Mean PEFR TLCO Serum IgE levels
Notes	Significant order effect was observed: data included here are from the first treatment period.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "randomised". Method not stated
Allocation concealment (selection bias)	Unclear risk	Information not available
Blinding (performance bias and detection bias) All outcomes	Low risk	Quote: "Double blind, double dummy"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Similar withdrawals in both arms
Selective reporting (reporting bias)	Low risk	All outcomes reported