Table 2. Characteristics of study participants (nutritional and health factors).

Variable	Category	All		High Income		Middle Income		Low Income		P Value	P Value
		n or mean ±SD	(%)	n or mean ±SD	(%)	n or mean ±SD	(%)	n or mean ±SD	(%)	unadjusted	adjusted a
Nutritional Factors
Body Mass Index(BMI)	<20	1001	15.3	421	15.1	290	14.6	290	16.6	0.139	0.80
	20–25	3965	60.7	1720	61.6	1216	61.2	1029	58.9
	≧25	1562	23.9	653	23.4	480	24.2	429	24.5
Frequency of eating meat or fish	daily	2383	36.5	1212	43.4	661	33.3	510	29.2	<0.01	0.00
	1>/week	3299	50.5	1277	45.7	1075	54.1	947	54.2
	≦1/week	381	5.8	162	5.8	107	5.4	112	6.4
	missing	465	7.1	143	5.1	143	7.2	179	10.2
Frequency of eating vegetables	daily	5053	77.4	2272	81.3	1508	75.9	1273	72.8	<0.01	0.27
	≦1/week	1067	16.3	368	13.2	355	17.9	344	19.7
	≦1/week	56	0.9	14	0.5	19	1.0	23	1.3
	missing	352	5.4	140	5.0	104	5.2	108	6.2
Health-related factors
Self-rated health	very good	739	11.3	347	12.4	208	10.5	184	10.5	<0.01	0.08
	good	4633	71.0	2028	72.6	1417	71.3	1188	68.0
	bad	943	14.4	351	12.6	294	14.8	298	17.0
	very bad	131	2.0	46	1.6	34	1.7	51	2.9
	missing	82	1.3	22	0.8	33	1.7	27	1.5
Activities of daily living	no need for help	6404	98.1	2765	99.0	1948	98.1	1691	96.7	<0.01	0.91
	needs partial help	45	0.7	10	0.4	13	0.7	22	1.3
	missing	79	1.2	19	0.7	25	1.3	35	2.0
Treatment of any diseases	yes	4572	70.0	1972	70.6	1397	70.3	1203	68.8	<0.01	0.10
	no	1520	23.3	650	23.3	478	24.1	392	22.4
	missing	436	6.7	172	6.2	111	5.6	153	8.8
"Yes" for Treatment of any disease
cancer	yes	183	2.8	72	2.6	60	3.0	51	2.9	<0.01	0.08
	no	5909	90.5	2550	91.3	1815	91.4	1544	88.3
	missing	436	6.7	172	6.2	111	5.6	153	8.8
heart disease	yes	612	9.4	258	9.2	195	9.8	159	9.1	<0.01	0.08
	no	5480	83.9	2364	84.6	1680	84.6	1436	82.2
	missing	436	6.7	172	6.2	111	5.6	153	8.8
stroke	yes	67	1.0	28	1.0	14	0.7	25	1.4	<0.01	0.02
	no	6025	92.3	2594	92.8	1861	93.7	1570	89.8
	missing	436	6.7	172	6.2	111	5.6	153	8.8
hypertension	yes	2433	37.3	1041	37.3	719	36.2	673	38.5	<0.01	0.04
	no	3659	56.1	1581	56.6	1156	58.2	922	52.7
	missing	436	6.7	172	6.2	111	5.6	153	8.8
diabetes	yes	713	10.9	297	10.6	207	10.4	209	12.0	<0.01	0.05
	no	5379	82.4	2325	83.2	1668	84.0	1386	79.3
	missing	436	6.7	172	6.2	111	5.6	153	8.8
hyperlipidemia	yes	718	11.0	369	13.2	217	10.9	132	7.6	<0.01	0.10
	no	5374	82.3	2253	80.6	1658	83.5	1463	83.7
	missing	436	6.7	172	6.2	111	5.6	153	8.8
arithritis	yes	613	9.4	250	8.9	199	10.0	164	9.4	<0.01	0.04
	no	5479	83.9	2372	84.9	1676	84.4	1431	81.9
	missing	436	6.7	172	6.2	111	5.6	153	8.8
respiratory disease	yes	200	3.1	81	2.9	51	2.6	68	3.9	<0.01	0.03
	no	5892	90.3	2541	90.9	1824	91.8	1527	87.4
	missing	436	6.7	172	6.2	111	5.6	153	8.8
gastric diseases	yes	333	5.1	128	4.6	116	5.8	89	5.1	<0.01	0.02
	no	5759	88.2	2494	89.3	1759	88.6	1506	86.2
	missing	436	6.7	172	6.2	111	5.6	153	8.8
liver disease	yes	87	1.3	40	1.4	27	1.4	20	1.1	<0.01	0.10
	no	6005	92.0	2582	92.4	1848	93.1	1575	90.1
	missing	436	6.7	172	6.2	111	5.6	153	8.8
mental illness	yes	66	1.0	19	0.7	26	1.3	21	1.2	<0.01	0.10
	no	6026	92.3	2603	93.2	1849	93.1	1574	90.0
	missing	436	6.6789216	172	6.2	111	5.6	153	8.8

^aAdjusted for sex, age, and area.