Amayasu 2000.

Study characteristics
Methods	Design: randomised controlled, double‐blind, cross‐over study Statistical analysis: Student's paired T‐test Duration: 8 weeks per treatment with 4‐week washout Conducted in Yokohama, Japan, and Boston, USA
Participants	Population: 17 participants randomised to 2 treatment sequences (clarithromycin‐placebo and placebo‐clarithromycin) Baseline characteristics: reported for population as a whole, since the study was a cross‐over design % male: 52.9 Mean age, years: 38.5 % on maintenance ICS: 0 % on maintenance LABA/ICS: 0 Mean % predicted FEV1: 76.2 Mean daily ICS dose, µg: 0 Chlamydophila infection: not reported Inclusion criteria: non‐smokers, aspirin tolerant, with mild or moderate asthma diagnosed according to the criteria of the ATS. All were in stable condition and had been free of symptoms for respiratory infections for ≥ 6 weeks. Exclusion criteria: people using oral or ICSs, theophylline, any anti‐leukotriene drug, any other anti‐inflammatory agents or clarithromycin
Interventions	Run‐in: wash‐out period ≥ 4 weeks between cross‐over Intervention: clarithromycin 200 mg twice per day Control: matching placebo
Outcomes	Blood eosinophils, blood neutrophils, serum ECP, sputum eosinophils, sputum neutrophils, sputum ECP, symptom score, FVC, FEV1, methacholine challenge
Notes	Funding: Aoki International Co, Ltd Study ID(s): not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomly assigned, no details.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Placebo of identical appearance used; described as double‐blind.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not described.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No mention of dropouts.
Selective reporting (reporting bias)	Unclear risk	Reported outcomes could be used in analysis, but unclear if others were missing (protocol registration not reported).
Other bias	Low risk	None noted.