Table 1 Baseline sample characteristics according to multimorbidity trajectory groups

Sex, n (%)^a

 < .001

 Male

1629 (51.9)

416 (50.7)

328 (43.6)

298 (48.2)

132 (61.4)

 Female

1512 (48.1)

405 (49.3)

425 (56.4)

320 (51.8)

83 (38.6)

Age(years), mean ± SD^b

56.4 ± 8.7

57.8 ± 8.5

56.5 ± 8.0

58.6 ± 8.9

59.2 ± 9.1

 < .001

Self-rated health, n (%)^a

 < .001

 Poor

218 (9.7)

86 (14.4)

124 (23.2)

70 (15.4)

42 (26.1)

 Fair

996 (44.3)

328 (54.8)

295 (55.1)

232 (51.0)

75 (46.6)

 Good

1032 (46.0)

184 (30.8)

116 (21.7)

153 (33.6)

44 (27.3)

Education, n (%)^a

 < .001

 No formal education

1254 (39.9)

383 (46.7)

364 (48.3)

248 (40.1)

106 (49.3)

 Primary school

687 (21.9)

183 (22.3)

153 (20.3)

140 (22.7)

47 (21.9)

 Middle school or above

1200 (38.2)

255 (31.0)

236 (31.4)

230 (37.2)

62 (28.8)

BMI(kg/m²), n (%)^a

 < .001

 < 18.5

152 (5.8)

36 (5.3)

51 (8.0)

10 (2.0)

19 (11.2)

 18.5–22.9

1272 (48.7)

284 (42.1)

323 (50.9)

161 (31.5)

85 (50.3)

 23.0–27.4

938 (35.8)

276 (40.9)

222 (35.1)

222 (43.4)

50 (29.6)

  ≥ 27.5

255 (9.7)

79 (11.7)

38 (6.0)

118 (23.1)

15 (8.9)

Occupation, n (%)^a

 < .001

 Agricultural work

1657 (53.0)

445 (54.2)

449 (59.9)

276 (45.0)

118 (54.9)

 Non-agricultural work

870 (27.8)

193 (23.5)

155 (20.6)

141 (23.0)

42 (19.5)

 Unemployed/retired

601 (19.2)

183 (22.3)

146 (19.5)

197 (32.0)

55 (25.6)

ADL disability, n (%)^a

 < .001

 No

2905 (93.6)

705 (86.9)

633 (84.6)

543 (88.7)

186 (87.7)

 Yes

200 (6.4)

106 (13.1)

115 (15.4)

69 (11.3)

26 (12.3)

Smoking, n (%)^a

 < .001

 No

1846 (58.8)

472 (57.5)

483 (64.1)

375 (60.7)

100 (46.5)

 Yes

1294 (41.2)

349 (42.5)

270 (35.9)

243 (39.3)

115 (53.5)

Alcohol drinking, n (%)^a

0.894

 No

1862 (59.3)

482 (58.8)

459 (61.0)

371 (60.1)

130 (60.5)

 Yes

1276 (40.7)

338 (41.2)

293 (39.0)

246 (39.9)

85 (39.5)

Sleep duration(h/day), n (%)^a

 < .001

  < 7

1242 (42.2)

381 (50.1)

389 (54.9)

258 (44.1)

88 (44.9)

 7-8

1443 (48.9)

310 (40.7)

265 (37.3)

266 (45.5)

87 (44.4)

  > 8

263 (8.9)

70 (9.2)

55 (7.8)

61 (10.4)

21 (10.7)

Marital status, n (%)^a

0.570

 Married/cohabitation

2871 (91.4)

738 (89.9)

688 (91.4)

556 (90.0)

194 (90.2)

 Single

270 (8.6)

83 (10.1)

65 (8.6)

62 (10.0)

21 (9.8)

Household expenditure (yuan), n (%)^a

0.172

 ≤ 2800

712 (26.7)

212 (29.6)

177 (27.3)

134 (25.2)

67 (36.1)

 2801–4846

726 (27.2)

174 (24.2)

176 (27.2)

134 (25.2)

41 (22.0)

 4847–8325

647 (24.3)

182 (25.4)

162 (25.0)

141 (26.5)

35 (18.8)

 > 8325

582 (21.8)

149 (20.8)

133 (20.5)

123 (23.1)

43 (23.1)

Social engagement, n (%)^a

0.828

 No

1571 (53.0)

412 (53.9)

396 (55.2)

307 (52.3)

108 (53.5)

 Yes

1391 (47.0)

352 (46.1)

321 (44.8)

280 (47.7)

94 (46.5)

Location of residence, n (%)^a

0.013

 Rural

2082 (66.3)

534 (65.0)

511 (67.9)

368 (59.5)

138 (64.2)

 Urban

1059 (33.7)

287 (35.0)

242 (32.1)

250 (40.5)

77 (35.8)

Health insurance, n (%)^a

0.320

No

229 (7.3)

65 (7.9)

48 (6.4)

34 (5.5)

12 (5.6)

Yes

2905 (92.7)

753 (92.1)

704 (93.6)

582 (94.5)

201 (94.4)