Choi 2020.

Study characteristics
Methods	RCT
Participants	Country: Korea, Single centre
Interventions	1.lansoprazole 30 mg. amoxicillin 1000 mg, clarithromycin 500 mg, twice daily for 7 days (n=912) 2.placebo, same number of pills, identical in appearance and taste for 7 days (n=914) Follow‐up: median duration of follow‐up for gastric cancer development =9.2 years (IQR, 6.2 to 10.6; maximum, 14.1), and the median duration of follow‐up for overall survival was 10.2 years (interquartile range, 8.9 to 11.6)
Outcomes	Development of gastric cancer; development of gastric cancer according to H. pylori eradication status during the follow‐up period; overall survival, and the development of adenoma
Notes	H. pylori eradication status was evaluated in 1587 participants during the follow‐up period. Eradication rate (70.1% (551/786) in the treatment group and 7.1% (57/801) in the placebo group
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"computer‐generated randomization sequence"
Allocation concealment (selection bias)	Low risk	“computer‐generated randomization sequence was kept at the trial pharmacy and was not accessible to the investigators who enrolled participants”.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	”Through‐out the trial, participants and investigators, including the endoscopist, pathologist, physician, research nurse, and statistician, were unaware of trial‐group assignments“.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	”Through‐out the trial, participants and investigators, including the endoscopist, pathologist, physician, research nurse, and statistician, were unaware of trial‐group assignments“.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Loss to follow up: 8.8% (80/912) vs 7.7% (70/914), balance between two arms.
Selective reporting (reporting bias)	Low risk	Reported prespecified outcomes.
Other bias	Low risk	No other risk of bias is noted.