3. Distribution of risk level among all participants, and risk of GC by risk group after excluding participants received endoscopy.

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.
Low	0	33,934	19	1,197	0.004	54.02% (43.04−64.64)	Reference
	1	13,965	21
High	≥2	30,730	47	654			1.67 (1.10−2.56)