Table 1 Descriptive statistics of analytic variables at baseline (n = 13,370)

Gender

 Female

3343

49.01

3837

58.59

 < 0.001

 Male

3478

50.99

2712

41.41

Education level

 No formal education (illiterate)

3498

51.28

4250

64.90

 < 0.001

 Primary school

1711

25.08

1455

22.22

 Junior high school

874

12.81

505

7.71

 Senior high school

407

5.97

186

2.84

 College or university graduate

331

4.85

153

2.34

Marital status

 Married

3084

45.21

1930

29.47

 < 0.001

 Single/divorced/widowed

3737

54.79

4619

70.53

Residence

 Town

3007

44.08

2411

36.81

 < 0.001

 Rural

3814

55.92

4138

63.19

Co-residence with family members

 Yes

5852

85.79

5078

77.54

 < 0.001

 No

969

14.21

1471

22.46

Medical insurance

Yes

3722

54.57

2894

44.19

 < 0.001

 No

3099

45.43

3655

55.81

Pension insurance

 Yes

1747

25.61

918

14.02

 < 0.001

 No

5074

74.39

5631

85.98

Mean

SD

Mean

SD

 Health behaviors

13.41

2.58

13.27

2.48

 < 0.001

 Age (years)

83.31

11.50

86.06

10.67

 < 0.001

 Chronic diseases

0.67

1.03

0.71

1.03

0.007

 ADL

17.65

1.31

17.30

1.94

 < 0.001

 Decision-making power in the family

3.89

1.17

3.39

1.17

 < 0.001

 Family economic status

3.12

0.57

2.78

0.67

 < 0.001

 Numbers of children

4.30

2.12

4.36

2.22

0.065