Table 2. Characteristics of subjects by quartile of monthly household income.
| Monthly household income (10,000 won) | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Variables | Lowest (≤120) |
Medium-lowest (121–250) |
Medium-highest (251–430) |
Highest (≥431) |
p-value | ||||
| N | e%(SE) | N | e%(SE) | N | e%(SE) | N | e%(SE) | ||
| Breast cancer prevalence (%) | 68 | 0.9(0.1) | 57 | 0.7(0.1) | 51 | 0.7(0.1) | 60 | 0.8(0.1) | 0.504 |
| Age (year) | <0.001 | ||||||||
| 19–44 | 756 | 18.1(0.7) | 2,887 | 51.3(0.8) | 3,715 | 60.1(0.7) | 3,535 | 56.6(0.7) | |
| 45–64 | 2,121 | 32.6(0.7) | 2,679 | 36.9(0.7) | 2,395 | 32.7(0.6) | 2,747 | 38.2(0.7) | |
| 65–74 | 4,049 | 49.3(0.8) | 1,198 | 11.8(0.4) | 695 | 7.2(0.3) | 534 | 5.1(0.3) | |
| Waist circumference (cm) | <0.001 | ||||||||
| <80 | 2,777 | 43.2(0.8) | 3,631 | 58.0(0.8) | 4,232 | 64.1(0.7) | 4,600 | 70.0(0.7) | |
| 80–90 | 2,601 | 35.9(0.7) | 2,132 | 28.9(0.7) | 1,871 | 26.0(0.6) | 1,679 | 22.9(0.6) | |
| >90 | 1,511 | 20.9(0.7) | 977 | 13.1(0.5) | 682 | 9.9(0.4) | 518 | 7.1(0.4) | |
| Survey year | <0.001 | ||||||||
| 2007 | 500 | 6.9(0.9) | 401 | 6.1(0.7) | 374 | 5.5(0.7) | 175 | 2.6(0.4) | |
| 2008 | 1,132 | 14.0(1.0) | 1,022 | 13.4(1.0) | 800 | 10.0(0.8) | 501 | 6.4(0.7) | |
| 2009 | 1,136 | 13.6(1.0) | 1,086 | 13.3(0.9) | 890 | 10.5(0.8) | 671 | 7.9(0.8) | |
| 2010 | 702 | 10.8(1.0) | 842 | 12.5(1.0) | 950 | 13.1(1.0) | 914 | 11.7(1.0) | |
| 2011 | 752 | 11.0(1.0) | 736 | 11.6(0.9) | 850 | 12.6(1.0) | 1,043 | 14.4(1.2) | |
| 2012 | 754 | 11.3(1.0) | 761 | 12.3(1.1) | 801 | 12.4(1.0) | 883 | 12.4(1.1) | |
| 2013 | 688 | 11.4(1.0) | 692 | 10.9(0.9) | 790 | 12.8(1.0) | 854 | 13.8(1.2) | |
| 2014 | 666 | 10.8(0.9) | 620 | 10.0(0.8) | 716 | 12.0(1.0) | 816 | 13.7(1.3) | |
| 2015 | 596 | 10.1(0.9) | 604 | 10.0(0.8) | 634 | 11.0(0.9) | 959 | 17.1(1.4) | |
| Education (year) | <0.001 | ||||||||
| ≤6 | 4,942 | 63.1(0.9) | 1,966 | 23.0(0.6) | 1,098 | 13.3(0.5) | 745 | 8.5(0.4) | |
| 7–9 | 701 | 10.8(0.5) | 947 | 13.0(0.5) | 679 | 9.4(0.4) | 514 | 7.2(0.4) | |
| 10–12 | 927 | 18.6(0.7) | 2,482 | 40.7(0.8) | 2,724 | 41.6(0.7) | 2,435 | 37.3(0.8) | |
| ≥13 | 356 | 7.5(0.4) | 1,369 | 23.2(0.7) | 2,304 | 35.7(0.8) | 3,122 | 47.1(0.8) | |
| Marital status | <0.001 | ||||||||
| Single | 390 | 9.8(0.6) | 731 | 15.0(0.6) | 831 | 16.5(0.6) | 1,022 | 19.5(0.6) | |
| Married | 6,536 | 90.2(0.6) | 6,033 | 85.0(0.6) | 5,974 | 83.5(0.6) | 5,794 | 80.5(0.6) | |
| Residential area | <0.001 | ||||||||
| Urban | 4,518 | 71.2(1.4) | 5,256 | 80.6(1.1) | 5,668 | 84.0(1.1) | 5,893 | 87.3(1.0) | |
| Rural | 2,408 | 28.8(1.4) | 1,508 | 19.4(1.1) | 1,137 | 16.0(1.1) | 923 | 12.7(1.0) | |
| Current smoking | 581 | 9.9(0.5) | 539 | 9.3(0.5) | 364 | 6.1(0.4) | 250 | 4.3(0.4) | <0.001 |
| Alcohol intake in past month | 3,074 | 48.7(0.8) | 4,205 | 65.8(0.7) | 4,655 | 71.0(0.7) | 4,889 | 74.6(0.6) | <0.001 |
| Physically activea | 2,622 | 37.5(0.7) | 2,684 | 40.3(0.7) | 2,610 | 38.6(0.7) | 2,553 | 38.1(0.7) | 0.047 |
| Cancer examination in the prior 2 yearsb | 3,766 | 51.8(0.8) | 3,829 | 53.6(0.7) | 3,991 | 55.8(0.7) | 4,400 | 60.9(0.7) | <0.001 |
| Previous pregnancyc | 6,446 | 89.7(0.6) | 5,946 | 84.0(0.7) | 5,867 | 81.9(0.6) | 5,685 | 78.8(0.6) | <0.001 |
| Current or past use of oral contraceptive | 1,502 | 20.8(0.6) | 1,225 | 16.9(0.6) | 951 | 13.6(0.5) | 830 | 11.9(0.5) | <0.001 |
| Post-menopausal | 3,270 | 40.1(1.0) | 1,635 | 18.8(0.6) | 1,106 | 13.3(0.5) | 1,018 | 13.6(0.6) | <0.001 |
| Age at menarche (year) | <0.001 | ||||||||
| <13 | 400 | 9.2(0.5) | 938 | 17.2(0.6) | 1,181 | 19.9(0.6) | 1,359 | 22.7(0.7) | |
| 13–14 | 1,444 | 24.1(0.7) | 2,370 | 37.4(0.7) | 2,784 | 41.6(0.7) | 2,971 | 44.2(0.7) | |
| 15–16 | 2,271 | 32.4(0.7) | 2,036 | 28.6(0.7) | 1,860 | 26.2(0.6) | 1,709 | 23.8(0.6) | |
| ≥17 | 2,607 | 34.4(0.8) | 1,337 | 16.7(0.5) | 919 | 12.2(0.5) | 736 | 9.4(0.4) | |
All values are given as number and estimated percentage (standard error).
aPhysically active was indicated as ‘yes’ when the subject walked for more than 30 min at a time and more than five times per week.
bCancer examination in the prior 2 years was indicated as ‘yes’ when the subject had undergone screening within the prior 2 years for any kind of cancer such as lung cancer, stomach cancer, and breast cancer etc.
cPrevious pregnancy was indicated as ‘yes’ when the a subject had ever been pregnant including normal pregnancy, ectopic pregnancy, still birth, spontaneous abortion, and induced abortion.