2. Distribution of risk level among target participants and risk of GC by risk group.

Cohort	Risk group	Risk level	N	GC	NNS*	P	Sensitivity [% (95% CI)]	aHR (95% CI)
Adjusted for age group (40−49, 50−59, 60−69 years old), sex, ethnicity and marital status (never married, married, divorced and widow); *, The number of participants who should undergo endoscopy screening to identify one incident case; GC, gastric cancer; NNS, number needed to screen; 95% CI, 95% confidence interval; aHR, adjusted hazard ratio.
All	Low	0	33,934	19	1,197	<0.001	69.47 (60.72−77.05)	Reference
		1	13,965	21
	High	≥2	42,015	91	462			2.37 (1.63−3.45)
Screening group	Low	0	17,150	11	1,221	<0.001	75.00 (63.52−83.92)	Reference
		1	6,046	8
	High	≥2	25,099	57	440			2.58 (1.53−4.34)
Control group	Low	0	16,784	8	1,176	0.001	61.82 (47.71−74.28)	Reference
		1	7,919	13
	High	≥2	16,916	34	498			2.15 (1.23−3.76)