Table 1. Demographic information of study samples from rural and urban areas (N = number).

Items	Groups	Urban(N = 19466)		Rural(N = 32035)		?2	P value
		n	%	N	%
Gender	Male	9445	48.52	15881	49.57	5.38	<0.001
	Female	10021	51.48	16154	50.43
Age(year)	18∼24	2660	13.66	5321	16.61	351.94	<0.001
	25∼34	4571	23.48	5873	18.33
	35∼44	4210	21.63	6343	19.80
	45∼54	2874	14.77	5821	18.17
	55∼64	2659	13.66	4830	15.08
	65∼	2492	12.80	3847	12.01
Marital status	Unmarried	3597	18.48	7217	22.53	218.48	<0.001
	Married	14757	75.81	22376	69.85
	Divorced	150	0.77	316	0.98
	Bereft	962	4.94	2126	6.64
Education	Primary school and below	6164	31.66	12121	37.84	1517.34	<0.001
	Junior school	5880	30.21	10086	31.48
	Senior high/technicalsecondary school	3928	20.18	7441	23.23
	Junior college	1631	8.38	1511	4.72
	University and above	1863	9.57	876	2.73
Occupation	Manager	625	3.21	574	1.79	10316.6	<0.001
	Business and service industry	3325	17.08	5044	15.75
	Skilled labour	1718	8.82	1753	5.47
	Clerk	985	5.06	1095	3.42
	Worker	610	3.13	9736	30.39
	Student	994	5.11	1746	5.45
	Retired servant	2363	12.14	2061	6.43
	Farmer	864	4.44	3625	11.32
	Unemployed	4200	21.58	5741	17.92
	Else	3782	19.43	660	2.06
Family per capitamonthly income	Lower	8992	46.19	19739	61.62	1167.82	<0.001
	Higher	10474	53.81	12296	38.38
Medical insurance	PEMI	103	0.53	1153	3.60	10894.2	<0.001
	MIE	1666	8.56	7817	24.40
	MIURR	18469	94.88	15953	49.80
	Self-pay	5742	29.50	18516	57.80
	CMI	3543	18.20	1217	3.80
	Others	1217	6.25	481	1.50

Note: Following the international practice, 50% of the median or average income in one country or a particular area is always considered as the low income standard [39]; Medical insurance: PEMI: Public expense medical insurance; MIE: Medical insurance for employees; MIURR: Medical insurance for urban and rural residents; CMI: Commercial medical insurance.