Table 1

Basic characteristics and dementia syndromes of participants with and without environmental tobacco smoke (ETS) exposure in the five-province study, China

	ETS exposure
Variable	No (n=3768)		Yes (n=2153)
	n	%	n	%	p Value
Age
Mean (SD)	72.99	7.53	72.02	7.43	<0.001
Sex
Men	1640	43.5	953	44.3	0.581
Women	2128	56.5	1200	55.7
Body mass index (kg/m²)
<25	2692	74.9	1546	74.9	0.971
25–29.9	765	21.3	436	21.1
≥30	137	3.8	81	3.9
Smoking status
Never	2610	69.3	1159	53.8	<0.001
Former	367	9.7	361	16.8
Current	791	21.0	633	29.4
Urban/rural
Urban	1986	52.7	783	36.4	<0.001
Rural	1782	47.3	1370	63.6
Educational level
College/university	234	6.2	88	4.1	<0.001
High secondary school	409	10.9	141	6.6
Secondary school	579	15.4	259	12.0
Primary school	900	23.9	598	27.8
Illiterate	1643	43.6	1064	49.5
Main occupation
Official/teacher	683	18.1	243	11.3	<0.001
Manual labourer	694	18.4	340	15.8
Business	23	0.6	16	0.7
Housewife	327	8.7	153	7.1
Other	291	7.7	122	5.7
Farmer	1748	46.4	1278	59.4
Annual income
Very satisfactory	343	9.1	179	8.3	0.519
Satisfactory	1617	43.0	943	43.9
Average	1518	40.4	849	39.6
Poor	281	7.5	175	8.2
Marriage
Married	2519	66.9	1622	75.4	<0.001
Widow	1126	29.9	476	22.1
Divorced	19	0.5	10	0.5
Never married	101	2.7	44	2.0
Having a religious belief
No	3227	85.8	1740	81.0	<0.001
Yes with religious activity	368	9.8	282	13.1
Yes without religious activity	168	4.5	125	5.8
Current drinking
No	3258	86.6	1745	81.0	<0.001
Yes	505	13.4	408	19.0
Visiting children or relatives
Every day	1564	41.6	945	44.0	<0.001
1–3/week	1287	34.2	611	28.4
≤1/month	908	24.2	592	27.6
Hypertension
No	1586	43.2	866	41.1	0.114
Yes	2082	56.8	1241	58.9
Diabetes
No	3514	93.4	2015	93.8	0.499
Yes	250	6.6	133	6.2
Stroke
No	3621	96.2	2065	96.3	0.893
Yes	143	3.8	80	3.7
Depressive syndrome (level)
0	3351	88.9	1883	87.5	0.214
1–2	214	5.7	143	6.6
3–5	203	5.4	127	5.9
Dementia syndrome (level)
No	2903	77.0	1523	70.7	<0.001
1–2	531	14.1	338	15.7
3–5	334	8.9	292	13.6