Table 2. Estimated prevalence of HBsAg and its risk factor analysis.

	Absolute number	Estimated prevalence		Bivariate analysis			Multivariable analysis
		Weighted %	95% CI	Crude odds ratio	95% CI	p-value	Adjusted odds ratio	95% CI	p-value
Overall	1,927	4.16	2.74–6.26
Sex
Female	1,016	3.51	1.74–6.93	ref
Male	1,001	4.81	3.53–6.53	1.39	0.72–2.66	0.29
Age (years)
1–4	342	0.15	0.03–0.71	0.04	0.01–0.17	<0.001	0.03	0.01–0.14	<0.001
5–9	179	2.84	0.76–10.03	0.70	0.26–1.93	0.47	0.59	0.21–1.62	0.30
10–14	120	0.79	1.43–4.22	0.19	0.04–1	0.05	0.21	0.04–1.04	0.06
15–19	328	4.80	2.13–10.45	1.21	0.54–2.71	0.62	1.22	0.62–2.42	0.56
20–24	122	10.67	5.01–21.31	2.87	1.24–6.63	0.02	2.28	1.13–4.57	0.02
25–29	185	10.43	5.51–18.85	2.80	1.23–6.37	0.02	2.67	1.27–5.6	0.01
30–34	167	3.99	1.62–9.48	1.00	0.38–2.66	1.00	0.97	0.45–2.07	0.93
35–39	115	5.06	1.92–12.65	1.28	0.38–4.33	0.67	1.50	0.59–3.77	0.39
40–	369	3.99	2.42–6.53	ref			ref
Place of residence (region)
Northern	525	8.97	4.98–15.64	8.21	2.83–23.81	0.001	2.78	1.16–6.64	0.02
Central	956	3.07	2.00–4.69	2.64	1.01–6.91	<0.05	2.29	0.95–5.53	0.06
Southern	446	1.19	0.51–2.75	ref			ref
Ethnicity
Laoloum	1,121	1.85	1.22–2.79	ref			ref
Khmu	293	8.50	4.00–17.16	4.93	1.91–12.69	0.003	3.64	1.95–6.80	<0.001
Hmong	322	11.16	6.58–18.28	6.66	3.26–13.59	<0.001	4.95	3.28–7.45	<0.001
Others	191	1.44	0.62–3.28	0.77	0.34–1.75	0.51	1.65	0.30–8.99	0.57
Operation history
Yes	122	8.39	3.18–20.33	2.23	0.99–4.99	0.05
No	1,805	3.95	2.70–5.73	ref
Blood transfusion history
Yes	101	4.52	1.53–12.62	1.09	0.32–3.64	0.89
No	1,826	4.17	2.70–6.39	ref
Sharing a toothbrush
Yes	107	6.95	3.49–13.33	1.77	0.88–3.57	0.10
No	1,820	4.05	2.63–6.20	ref
Tattoo
Yes	133	6.30	2.45–15.22	1.31	0.43–4.04	0.61
No	1,794	4.87	3.08–7.65	ref
Sharing a razor
Yes	49	11.34	5.31–22.60	2.59	1.03–6.52	<0.05
No	1,878	4.71	2.98–7.37	ref
Sharing needle for drug injection
Yes	47	3.51	0.93–12.39	0.70	0.14–3.48	0.64
No	1,880	4.93	3.14–7.66	ref

HBsAg, hepatitis B surface antigen; CI, confidence interval.