Table 1 Key features of the study sample at baseline

Low

Junior high school

5902

(18.9)

2937

(19.4)

2965

(18.4)

1.0

0.027

Middle

High school

17,940

(57.5)

7868

(52.0)

10,072

(62.6)

−10.6

<  0.001

Junior college

2248

(7.2)

368

(2.4)

1880

(11.7)

−9.3

<  0.001

Other

205

(0.7)

116

(0.8)

89

(0.6)

0.2

0.020

Total

20,393

(65.3)

8352

(55.2)

12,041

(74.9)

−19.7

<  0.001

High

College

4658

(14.9)

3617

(23.9)

1041

(6.5)

17.4

<  0.001

Graduate school

257

(0.8)

221

(1.5)

36

(0.2)

1.2

<  0.001

Total

4915

(15.7)

3838

(25.4)

1077

(6.7)

18.7

<  0.001

6788

(21.7)

3077

(20.3)

3711

(23.1)

−2.7

<  0.001

16,829

(53.9)

12,738

(84.2)

4091

(25.4)

58.8

<  0.001

8364

(26.8)

1380

(9.1)

6984

(43.4)

−34.3

<  0.001

6017

(19.3)

1009

(6.7)

5008

(31.1)

−24.5

<  0.001

9346

(29.9)

7307

(48.3)

2039

(12.7)

35.6

<  0.001

1420

(4.5)

1293

(8.5)

127

(0.8)

7.8

<  0.001

15,348

(49.2)

8141

(53.8)

7207

(44.8)

9.0

<  0.001

7444

(23.9)

4597

(30.4)

2847

(17.7)

12.7

<  0.001

2465

(7.9)

1240

(8.2)

1225

(7.6)

0.6

0.057

9747

(31.2)

4778

(31.6)

4969

(30.9)

0.7

0.189

13,078

(41.9)

6145

(40.6)

6933

(43.1)

−2.5

<  0.001

4322

(13.8)

2172

(14.4)

2150

(13.4)

1.0

0.011

1080

(3.5)

532

(3.5)

548

(3.4)

0.1

0.597

277

(0.9)

151

(1.0)

126

(0.8)

0.2

0.043

Age

M

54.7

54.7

54.7

0.0

0.460

SD

(2.7)

(2.7)

(2.7)

Household spending^a

M

188.9

195.0

183.1

11.9

<  0.001

(monthly, thousand yen)

SD

(180.3)

(206.4)

(151.1)

N

31,210

15,127

16,083