Table 1 Socio-demographic characteristics of study participants aged 45 years and older in China, 2011–2018

Multimorbidity

6,412 (37.87%)

6,381 (43.68%)

7,853 (56.02%)

7,981 (61.14%)

Number of body pain

1.27 (0.02)

0.93 (0.02)

1.66 (0.03)

2.92 (0.03)

Sleep duration

6.88 (0.02)

6.81 (0.02)

6.99 (0.02)

6.92 (0.02)

Depression

 No

10,047 (65.31%)

9,002 (69.72%)

8,767 (67.16%)

7,140 (63.11%)

 Yes

5,335 (34.69%)

3,909 (30.28%)

4,286 (32.84%)

4,174 (36.89%)

Age (years)

58.44 (0.08)

61.46 (0.08)

63.02 (0.08)

65.65 (0.08)

Sex

 Male

8,201 (48.44%)

6,935 (48.55%)

6,716 (48.31%)

5,953 (48.22%)

 Female

8,730 (51.56%)

7,349 (51.45%)

7,186 (51.69%)

6,391 (51.78%)

Marital status

 Single

2,493 (14.73%)

2,292 (16.04%)

2,333 (16.78%)

2,351 (19.04%)

 Married/partnered

14,428 (85.27%)

11,990 (83.96%)

11,569 (83.22%)

9,993 (80.96%)

Educational attainment

 Illiterate

7,268 (42.94%)

6,338 (44.37%)

6,085 (43.77%)

5,310 (43.02%)

 Primary school

3,466 (20.48%)

2,970 (20.80%)

2,884 (20.75%)

2,607 (21.12%)

 Secondary school and above

6,191 (36.58%)

4,976 (34.83%)

4,933 (35.48%)

4,427 (35.86%)

Residence status

 Rural

8,469 (50.02%)

7,694 (53.87%)

7,649 (55.02%)

6,843 (55.44%)

 Urban

8,462 (49.98%)

6,590 (46.13%)

6,253 (44.98%)

5,501 (44.56%)

Health insurance

 Private insurance/others

1,418 (8.49%)

706 (5.00%)

1,368 (9.88%)

501 (4.07%)

 Public insurance

15,290 (91.51%)

13,393 (95.00%)

12,470 (90.12%)

11,831 (95.93%)

Geographic locations

 East locations

7,510 (44.36%)

6,242 (43.70%)

5,911 (42.52%)

5,193 (42.07%)

 Middle locations

4,355 (25.72%)

3,807 (26.65%)

3,783 (27.22%)

3,405 (27.59%)

 West locations

5,066 (29.92%)

4,235 (29.65%)

4,207 (30.26%)

3,746 (30.34%)

Household consumption quartiles

 Quartile 1 (the most deprived)

3,149 (22.32%)

2,267 (24.18%)

2,453 (26.55%)

2,752 (26.91%)

 Quartile 2

3,159 (22.39%)

2,318 (24.73%)

2,400 (25.98%)

2,572 (25.15%)

 Quartile 3

3,431 (24.32%)

2,400 (25.60%)

2,180 (23.60%)

2,548 (24.91%)

 Quartile 4 (the most affluent)

4,368 (30.96%)

2,390 (25.49%)

2,206 (23.88%)

2,356 (23.03%)

ADLs

 Unimpaired

13,960 (84.04%)

11,567 (81.92%)

10,762 (77.96%)

9,601 (77.98%)

 Impaired

2,651 (15.96%)

2,552 (18.08%)

3,043 (22.04%)

2,710 (22.02%)

IADLs

 Unimpaired

13,318 (79.34%)

10,788 (76.14%)

10,223 (73.83%)

8,901 (72.29%)

 Impaired

3,469 (20.66%)

3,381 (23.86%)

3,624 (26.17%)

3,411 (27.71%)