Table 1 Characteristics of the study subjects at baseline and at the 1-year follow-up and the percentages of declines in higher-level activities of daily living during the 12-month study period by baseline characteristics

Depressive symptoms (0)

  Not severe

475 (90)

–

–

71 (15)

42 (9)

37 (8)

57 (12)

  Severe

55 (10)

–

–

18 (33)

18 (33)

8 (15)

11 (20)

    p value

0.001

<0.0001

0.09

0.09

Age^a (0)

  65–74

233 (44)

27 (11)

230 (89)

33 (14)

23 (10)

16 (7)

27 (12)

  75+

297 (56)

37 (11)

293 (89)

56 (19)

37 (13)

29 (10)

41 (14)

    p value

0.79

0.15

0.35

0.23

0.45

Gender (0)

  Male

277 (52)

27 (9)

276 (91)

48 (17)

39 (14)

19 (7)

37 (13)

  Female

253 (48)

37 (13)

247 (87)

41 (16)

21 (8)

26 (10)

31 (12)

    p Value

0.11

0.72

0.03

0.16

0.70

Education (62)

  <High school

199 (43)

21 (9)

202 (91)

37 (19)

22 (11)

17 (9)

28 (14)

  High school+

269 (57)

34 (12)

260 (88)

43 (16)

32 (12)

20 (7)

33 (12)

    p value

0.43

0.45

0.78

0.66

0.57

Individual income; 1000 yen/month (68)

  <99

199 (43)

29 (13)

188 (87)

37 (19)

22 (11)

22 (11)

32 (16)

  100–199

124 (27)

14 (10)

125 (90)

20 (16)

16 (13)

10 (8)

13 (11)

  200+

139 (31)

8 (5)

141 (95)

19 (14)

14 (11)

5 (4)

12 (9)

    p value

0.04

0.48

0.76

0.05

0.09

Family composition (1)

  Living alone

43 (8)

6 (11)

48 (89)

7 (16)

4 (9)

2 (5)

9 (21)

  With spouse (2 people)

255 (43)

24 (10)

220 (90)

32 (14)

25 (11)

16 (7)

24 (11)

  3+ people

261 (49)

34 (12)

253 (88)

50 (19)

31 (12)

26 (10)

35 (13)

    p value

0.76

0.34

0.88

0.35

0.17

Physical health (PCS score^b) (2)

  High

267 (51)

18 (6)

275 (94)

38 (14)

24 (9)

36 (12)

29 (11)

  Low

261 (49)

45 (15)

246 (85)

51 (20)

35 (13)

55 (19)

39 (15)

    p value

0.0003

0.10

0.11

0.03

0.16

Chronic disease (1)

  Yes

412 (78)

55 (12)

400 (88)

73 (18)

52 (13)

37 (9)

55 (13)

  No

117 (22)

9 (7)

120 (93)

16 (14)

8 (7)

8 (7)

13 (11)

    p value

0.10

0.30

0.08

0.46

0.52

Smoking (0)

  Never

308 (58)

40 (12)

305 (88)

51 (17)

31 (10)

27 (9)

38 (12)

  Ever

158 (30)

18 (11)

150 (89)

29 (18)

22 (14)

14 (9)

22 (13)

  Current

64 (12)

6 (8)

67 (92)

9 (14)

7 (11)

4 (6)

8 (13)

    p value

0.70

0.85

0.46

0.79

0.89

Alcohol drinking (0)

  Never

257 (50)

39 (13)

256 (87)

45 (18)

25 (10)

24 (9)

37 (14)

  Less than 1/week

92 (17)

10 (10)

87 (90)

11 (12)

9 (10)

7 (8)

7 (8)

  1–6/week

75 (14)

9 (11)

71 (89)

17 (28)

13 (17)

5 (7)

10 (13)

  Every day

106 (20)

6 (5)

109 (95)

16 (15)

13 (12)

9 (9)

14 (13)

    p value

0.14

0.30

0.30

0.88

0.42

Exercise habits (1)

  Yes

298 (56)

34 (11)

288 (89)

48 (16)

36 (12)

25 (9)

35 (11)

  No

232 (44)

30 (11)

234 (89)

41 (18)

24 (10)

20 (9)

33 (14)

    p value

0.76

0.63

0.53

0.92

0.39

TMIG-IC^c score (score range)

  Total score (0–13)

10.5 ± 2.6

8.9 ± 3.0

10.7 ± 2.4

11.2 ± 2.5

    p value

<0.001

  Social role (0–4)

3.4 ± 1.0

2.6 ± 1.4

3.5 ± 1.0

3.5 ± 0.9

    p value

<0.001

  Intellectual activities (0–4)

3.5 ± 0.9

3.0 ± 1.1

3.5 ± 0.8

3.6 ± 0.8

    p value

0.001

 Instrumental self-maintenance (0–5)

3.7 ± 1.3

3.3 ± 1.6

3.8 ± 1.3

3.0 ± 1.3

    p value

0.02