Peterson 1996.

Methods	Design: randomised, placebo‐controlled, 4‐armed trial
Participants	Number assigned: 89 adults and elderly (macrolide n = 55, placebo n = 34) Age in years (mean (range)): macrolide: 51.7 (26 to 77), placebo: 48.4 (22 to 76) Setting: secondary care
Interventions	Indication: duodenal ulcer Type of macrolide: clarithromycin Route: per oral Dose per day: 1500 mg Duration of treatment: 14 days Total treatment dose: 21,000 mg
Outcomes	Adverse events stated as an outcome in trial registration/protocol/paper: yes Adverse events ascertainment: physical + clinical examination (lab tests) Adverse events: data reported Antimicrobial resistance: not reported Death: not reported
Funding sources	Study supported by Glaxo Wellcome Inc.
Notes	Concomitant medication: yes Note: this is a 4‐armed randomised controlled trial (placebo, clarithromycin, ranitidine bismuth citrate, ranitidine bismuth citrate + clarithromycin). Importantly, the participants in both the macrolide and the placebo group received a placebo at some time to ensure blinding in all groups.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Sequence generation not described.
Allocation concealment (selection bias)	Unclear risk	Allocation not described.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Identical‐appearing placebo
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Participants and clinicians blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Dropouts due to adverse events reported.
Selective reporting (reporting bias)	Low risk	Adverse events stated as an outcome, standardised ascertainment, and adverse events reported.
Other bias	Unclear risk	Participants were assigned in a 2:1 ratio.