Table 1. The demographic characteristics of the participants of the BCCS-CW, 2020.
| Variable | Overall N (%) | Breast cancer N (%) | Control N (%) | t/χ2 | P value |
| Abbreviation: IQR=interquartile range; BCCS-CW=the Breast Cancer Cohort Study in Chinese Women; SD=standard deviation; CNY=Chinese Yuan. | |||||
| Age, mean (SD) | 50.78±11.01 | 53.34±9.22 | 50.75±11.02 | 7.35 | <0.001 |
| Sleep duration, mean (SD) | 7.29±1.90 | 7.09±2.16 | 7.29±1.90 | –2.41 | 0.016 |
| CES-D score, median (IQR) | 3.00 (7.00) | 4.00 (6.00) | 3.00 (7.00) | 2.24 | 0.019 |
| Education | 8.60 | 0.014 | |||
| Primary school and below | 33,402 (53.05) | 393 (56.30) | 33,009 (53.01) | ||
| Junior/senior high school/technical school | 27,175 (43.16) | 292 (41.83) | 26,883 (43.18) | ||
| Junior college and above | 2,384 (3.79) | 13 (1.87) | 2,371 (3.81) | ||
| Marital status | 1.38 | 0.240 | |||
| Unmarried | 6,040 (9.58) | 58 (9.29) | 5,982 (9.60) | ||
| Married | 56,978 (90.42) | 642 (91.71) | 56,336 (90.40) | ||
| Average monthly income, CNY | 21.83 | <0.001 | |||
| <1,000 | 12,842 (20.40) | 168 (24.07) | 12,674 (20.36) | ||
| 1,000–2,999 | 30,147 (47.89) | 355 (50.86) | 29,792 (47.85) | ||
| 3,000–4,999 | 13,994 (22.23) | 106 (15.19) | 13,888 (22.31) | ||
| ≥5,000 | 5,978 (9.49) | 69 (9.88) | 5,909 (9.49) | ||
| Menopause | 89.64 | <0.001 | |||
| Yes | 27,495 (43.63) | 368 (52.57) | 27,127 (43.53) | ||
| No | 32,453 (51.50) | 258 (36.86) | 32,195 (51.67) | ||
| Benign breast disease history | 2271.40 | <0.001 | |||
| Yes | 933 (1.49) | 162 (23.18) | 771 (1.24) | ||
| No | 61,847 (98.51) | 537 (76.82) | 61,310 (98.76) | ||
| Sleep satisfaction | 33.55 | <0.001 | |||
| Very satisfied | 13,542 (21.58) | 96 (13.73) | 13,446 (21.67) | ||
| Satisfied | 27,395 (43.65) | 313 (44.78) | 27,082 (43.64) | ||
| Neutral | 15,934 (25.39) | 190 (27.18) | 15,744 (25.37) | ||
| Dissatisfied | 5,502 (8.77) | 94 (13.45) | 5,408 (6.71) | ||
| Very dissatisfied | 382 (0.61) | 6 (0.86) | 376 (0.61) | ||
| Economic status | 22.72 | <0.001 | |||
| Very good | 2,815 (4.47) | 25 (3.58) | 2,790 (4.48) | ||
| Good | 8,025 (12.75) | 75 (10.74) | 7,950 (12.77) | ||
| Common | 48,313 (76.73) | 516 (73.93) | 47,797 (76.77) | ||
| Poor | 3,333 (5.29) | 67 (9.60) | 3,266 (6.25) | ||
| Very poor | 475 (0.75) | 15 (2.15) | 460 (0.74) | ||
| Social status | 5.02 | 0.025 | |||
| Very good | 4,265 (6.77) | 42 (6.02) | 4,223 (6.78) | ||
| Good | 9,356 (14.86) | 92 (13.18) | 9,264 (14.88) | ||
| Common | 47,464 (75.39) | 530 (75.93) | 46,934 (75.38) | ||
| Poor | 1,659 (2.63) | 30 (4.30) | 1,629 (2.62) | ||
| Very poor | 217 (0.34) | 4 (0.57) | 213 (0.34) | ||