Table 2 General characteristics in subgroups of different educational levels, obtained at the end of the study period

  Age (years)

63.8 ± 9.6

59.5 ± 10.7

47.7 ± 13.5

44.8 ± 15.2

<0.001

  Female (%)

75.4

52.5

41.5

30.4

<0.001

  Current smoker (%)

14.9

28.6

38.5

41.5

<0.001

  Drink alcohol^b (%)

7.6

20.9

33.5

36.5

<0.001

Disease history (%)

37.1

25.3

17.2

14.1

<0.001

  Coronary heart disease

14.6

10.6

6.1

2.3

<0.001

  Stroke

5.8

5.9

3.6

1.2

0.137

  Diabetes

4.6

5.5

3.6

1.8

0.004

  Hypertension

41.0

30.3

18.8

22.2

<0.001

Physical examination

  SBP (mmHg)^a

146.9 ± 6.3

144.0 ± 7.0

136.4 ± 8.8

134.4 ± 9.9

<0.001

  DBP (mmHg)^a

86.4 ± 1.3

86.5 ± 1.6

85.5 ± 1.8

85.4 ± 2.0

<0.001

  BMI (kg/m²)^a

24.8 ± 0.2

24.7 ± 0.2

24.5 ± 0.3

24.4 ± 0.2

<0.001

Province (%)

<0.001

  Liaoning

8.1

43.1

43.1

5.8

  Hebei

13.4

35.4

37.7

13.4

  Shanxi

13.6

41.5

37.4

7.5

  Shaanxi

9.1

36.1

42.6

12.2

  Ningxia

42.2

27.4

25.9

4.6