Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Ulcer prevention
RCT	102 people with H pylori and taking NSAIDs, with a history of dyspepsia or peptic ulceration, but without active ulcers	Cumulative 6-month risk of peptic ulcer 12% with 1-week quadruple eradication regimen 34% with omeprazole alone for 1 week Absolute numbers not reported	P = 0.009	Effect size not calculated	quadruple eradication regimen
RCT	102 people with H pylori and taking NSAIDs, with a history of dyspepsia or peptic ulceration, but without active ulcers	Cumulative 6-month risk of bleeding peptic ulcer 4% with 1-week quadruple eradication regimen 27% with omeprazole alone for 1 week Absolute numbers not reported	P = 0.003	Effect size not calculated	quadruple eradication regimen
RCT	150 people taking naproxen with H pylori and a bleeding peptic ulcer that healed with omeprazole treatment Subgroup analysis	Cumulative 6-month risk of developing a bleeding ulcer 19% with 1-week triple eradication regimen (bismuth subcitrate plus tetracycline plus metronidazole) 4% with 6 months' maintenance treatment with omeprazole Absolute numbers not reported	ARI 14.4% 95% CI 4.4% to 24.4%	Effect size not calculated	omeprazole
RCT	250 people taking low-dose aspirin with H pylori and a bleeding peptic ulcer that healed with omeprazole treatment Subgroup analysis	Cumulative 6-month risk of developing a bleeding ulcer 1.9% with 1-week triple eradication regimen (bismuth subcitrate plus tetracycline plus metronidazole) 0.9% with 6 months' maintenance treatment with omeprazole Absolute numbers not reported	Absolute difference +1.0% 95% CI –1.9% to +3.9% Given the much lower risk of bleeding with low-dose aspirin compared with naproxen, the RCT may have been underpowered with respect to aspirin, although a large absolute effect can be excluded		Not significant