Table 1 Characteristics of study participants
|  | All (n = 6074) | Male (n = 3016) | Female (n = 3058) | P value of gender difference |
|---|---|---|---|---|
Cognitive function, mean ± SD |  |  |  |  |
 2011 | 10.04 ± 4.13 | 11.18 ± 3.68 | 8.89 ± 4.24 | < 0.001 |
 2013 | 9.56 ± 4.51 | 10.82 ± 4.04 | 8.31 ± 4.60 | < 0.001 |
 2015 | 9.03 ± 4.58 | 10.26 ± 4.10 | 7.81 ± 4.70 | < 0.001 |
 2018 | 8.91 ± 4.89 | 9.97 ± 4.36 | 7.76 ± 5.11 | < 0.001 |
The living arrangement, n (%) |  |  |  | < 0.001 |
 Living alone | 482 (7.94) | 172 (5.70) | 310 (10.14) |  |
 Living with spouse | 2728 (44.91) | 1443 (47.84) | 1285 (42.02) |  |
 Living with adult children | 639 (10.52) | 186 (6.17) | 453 (14.81) |  |
 Living with spouse and adult children | 2103 (34.62) | 1169 (38.76) | 934 (30.54) |  |
 Living with others | 122 (2.01) | 46 (1.53) | 76 (2.49) |  |
Age (years at baseline), mean ± SD | 67.24 ± 5.99 | 67.30 ± 5.90 | 67.18 ± 6.07 | 0.410 |
Geographic residence, n (%) | Â | Â | Â | 0.208 |
 Rural | 3627 (59.71) | 1825 (60.51) | 1802 (58.93) |  |
 Urban | 2447 (40.29) | 1191 (39.49) | 1256 (41.07) |  |
Education, n (%) |  |  |  | < 0.001 |
 No formal education | 1729 (28.47) | 382 (12.67) | 1347 (44.05) |  |
 Capable of reading and/or writing | 1300 (21.40) | 640 (21.22) | 660 (21.58) |  |
 Primary school | 1600 (26.34) | 1004 (33.29) | 596 (19.49) |  |
 Middle school and above | 1445 (23.79) | 990 (32.82) | 455 (14.88) |  |
Working status, n (%) |  |  |  | < 0.001 |
 No | 2710 (44.62) | 1138 (37.73) | 1572 (51.41) |  |
 Yes | 3364 (55.38) | 1878 (62.27) | 1486 (48.59) |  |
The number of physical comorbidities, n (%) |  |  |  | < 0.001 |
 0 | 1858 (30.59) | 1000 (33.16) | 858 (28.06) |  |
 1–2 | 2972 (48.93) | 1470 (48.74) | 1502 (49.12) |  |
 ≥ 3 | 1244 (20.48) | 546 (18.10) | 698 (22.83) |  |
Feeling pain, n (%) |  |  |  | < 0.001 |
 No | 4050 (66.68) | 2233 (74.04) | 1817 (59.42) |  |
 Yes | 2024 (33.32) | 783 (25.96) | 1241 (40.58) |  |
IADLs, n (%) |  |  |  | < 0.001 |
 Unimpaired | 4630 (76.23) | 2452 (81.30) | 2178 (71.22) |  |
 Impaired | 1444 (23.77) | 564 (18.70) | 880 (28.78) |  |
Depressive symptoms, n (%) |  |  |  | < 0.001 |
 No | 3854 (63.45) | 2134 (70.76) | 1720 (56.25) |  |
 Yes | 2220 (36.55) | 882 (29.24) | 1338 (43.75) |  |
Social activity participation, n (%) | Â | Â | Â | 0.238 |
 No | 3198 (52.65) | 1565 (51.89) | 1633 (53.40) |  |
 Yes | 2876 (47.35) | 1451 (48.11) | 1425 (46.60) |  |
Number of adult children, n (%) |  |  |  | < 0.001 |
 1 | 582 (9.58) | 340 (11.27) | 242 (7.91) |  |
 2–3 | 3041 (50.07) | 1588 (52.65) | 1453 (47.51) |  |
 ≥ 4 | 2451 (40.35) | 1088(36.07) | 1363 (44.57) |  |
Average schooling year of children (Centered), mean ± SD | 8.41 ± 3.60 | 8.58 ± 3.62 | 8.23 ± 3.57 | < 0.001 |
Household expenditure per capita(log), mean ± SD | 8.54 ± 0.94 | 8.57 ± 0.93 | 8.52 ± 0.96 | 0.018 |