Table 1 Basic feature of COPD patients

Sex

  male

3,930

47.8

  female

4,287

52.2

Age (years)

  <40

620

7.6

  40~

2,566

31.2

  60~

4,297

52.3

  80~

734

8.9

Marital status

  unmarried

172

2.1

  married

5,890

71.7

  divorced

43

0.5

  widowed

2,112

25.7

Living arrangement

  live alone

1,018

12.4

  live with spouse

4,547

55.3

  live with children

2,315

28.2

Others

337

4.1

Education

  illiterate

4,665

56.8

  primary school

1739

21.2

  junior school

1,090

13.3

  high school

723

8.8

Household income per month (yuan)

  <300

3,541

43.1

  300~

2,337

28.4

  500~

1,613

19.6

  1,000~

726

8.8

Disease history (years)

  <5

796

9.7

  5~

1,048

12.8

  10~

1,928

23.5

  20~

3,903

47.5

  30~

542

6.6