Table 4. Factors associated with Helicobacter pylori seropositivity in 16,885 asymptomatic subjects without a history of receiving H. pylori eradication and gastric operation.

Variable category		Total	Seropositivity	Multivariable Analysis
		No	No [%]	OR	95% CI	P-value
All		16,885	7416 [43.9]
Gender	Male	8,950	5262 [47.1]	1.34	1.23–1.46	< 0.0001
	Female	7,935	3857 [40.4]	ref
Age Group (years)	16–19	17	1 [5.9]	0.000	0.000	0.999
	20–29	630	86 [13.7]	ref
	30–39	2,263	645 [28.5]	2.73	2.00–3.72	< 0.0001
	40–49	4,870	2021 [41.5]	5.33	3.95–7.21	< 0.0001
	50–59	5,478	2725 [49.7]	7.32	5.42–9.88	< 0.0001
	60–69	2,656	1219 [54.1]	8.78	6.41–11.85	< 0.0001
	≥70	971	501 [51.6]	7.30	5.24–10.15	< 0.0001
Geographical areas	Seoul	10,189	4222 [41.4]	ref
	Gyeonggi	3,142	1350 [43.0]	0.98	0.90–1.07	0.66
	Chungcheong	595	299 [50.3]	1.31	1.07–1.61	0.009
	Kyungsang	1,906	965 [50.6]	1.45	1.27–1.64	< 0.0001
	Cholla	502	288 [57.4]	1.24	0.95–1.60	0.11
	Kangwon	343	164 [47.8]	1.57	1.04–2.35	0.03
	Jeju	208	128 [61.5]	1.62	0.95–2.76	0.076
Household income level †	Low	1,066	491 [46.1]	1.19	0.99–1.42	0.07
	Medium	6,612	2965 [44.8]	1.10	1.03–1.19	0.006
	High	8,200	3542 [43.2]	ref
Educational level‡	Low	640	339 [53.0]	1.00	0.99–1.26	0.995
	Medium	2,269	1105 [48.7]	1.17	1.05–1.31	0.006
	High	13,829	5900 [42.7]	ref
Smoking	Nonsmoker	12,538	5425 [43.3]	ref
	Ex-smoker	1,656	705 [42.6]	0.96	0.84–1.08	0.47
	Current smoker	2,673	1276 [47.7]	0.97	0.86–1.05	0.34

Subjects with missing values were excluded. Odds ratio (OR) was mutually adjusted for all factors.

HP, Helicobacter pylori; No, number; OR, odds ratio; CI, confidence interval

^†Household income was classified as low (less than US $ 3,000 per month), medium (US $ 3,000 to 10,000 per month), or high (more than US $ 10,000 per month)

^‡Educational level was classified as low (middle school graduates or less), medium (high school graduates or university dropouts), or high (university graduates or graduates of a postgraduate course). Bold font indicates statistical significance.