Bukowskyj 1987.

Methods	Randomised controlled trial Cross‐over design ‐ double‐blinded, rule = time (1 week)
Participants	Ten patients admitted, 8 (4 male) completed the study Mean age 64.8 (SD = 8) years Severity of asthma: Inclusion criteria: reversible obstructive airway disease, clinically stable, FEV1 < 75% predicted value Exclusion criteria: congestive heart failure, hepatic disease, ingestion of cimetidine, ingestion of oral contraceptives Prescribed medication: 7 patients took oral theophylline and salbutamol; 3 patients took inhaled beclomethasone dipropionate; 1 patient took inhaled beclomethasone dipropionate and prednisolone Control measure: refrained from caffeine, other methylxanthine‐containing substances and orally‐administered beta‐agonists for 12 h prior to and throughout 8 h study. Refrained from inhaling beta‐agonists for 6 h prior to and throughout the 8 h study period.
Interventions	5 mg/kg caffeine versus placebo as a solution in a juice drink
Outcomes	% change FEV1, % change FVC, % change FEF25‐75, % change Vmax50, % change Vmax25, FEV1 % predicted, pulse, blood pressure
Notes	Administration of corticosteroids was continued unchanged in those patients receiving long‐term therapy with these drugs
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No details
Allocation concealment (selection bias)	Low risk	Allocated by pharmacist
Blinding (performance bias and detection bias) All outcomes	Low risk	Quote: "Double‐blinded" Quote: "The medication code was known only to the hospital pharmacists."
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "The two patients who withdrew did so because they found the repeated spirometric tests unacceptably tiring. There was one patient who completed the study except for the last four h of the placebo day when she developed dyspnoea." No data used from these patients